Sciendum tamen est quod in rebus naturalibus aliquid praeexistit in potentia dupliciter: uno modo in potentia activa completa, quando scilicet principium intrinsecum sufficienter potest perducere in actum perfectum, sicut patet in sanatione: ex virtute enim naturali quae est in aegro aeger ad sanitatem perducitur; alio modo in potentia passiva, quando scilicet principium intrinsecum non sufficit ad educendum in actum, sicut patet quando ex aere fit ignis: hoc enim non poterat fieri per aliquam virtutem in aere existentem. Quando igitur praeexistit aliquid in potentia activa completa, tunc agens extrinsecum non agit nisi adiuvando agens intrinsecum et ministrando ei ea quibus possit in actum exire; sicut medicus in sanatione est minister naturae quae principaliter operatur, confortando naturam et apponendo medicinas quibus velut instrumentis natura utitur ad sanationem. Quando vero aliquid praeexistit in potentia passiva tantum, tunc agens extrinsecum est quod educit principaliter de potentia in actum; sicut ignis facit de aere, qui est potentia ignis, actu ignem. Scientia ergo praeexistit in addiscente in potentia non pure passiva sed activa, alias homo non posset per se ipsum acquirere scientiam. Sicut ergo aliquis dupliciter sanatur, uno modo per operationem naturae tantum, alio modo a natura cum adminiculo medicinae, ita etiam est duplex modus acquirendi scientiam: unus quando naturalis ratio per se ipsam devenit in cognitionem ignotorum, et hic modus dicitur inventio; alius quando naturali rationi aliquis exterius adminiculatur, et hic modus dicitur disciplina. We must bear in mind, nevertheless, that in natural things something can pre-exist in potency in two ways. In one, it is in an active and completed potency, as when an intrinsic principle has sufficient power to flow into perfect act. Healing is an obvious example of this, for the sick person is restored to health by the natural power within him. The other appears in a passive potency, as happens when the internal principle does not have sufficient power to bring it into act. This is clear when air becomes fire, for this cannot result from any power existing in the air. Therefore, when something pre-exists in active completed potency, the external agent acts only by helping the internal agent and providing it with the means by which it can enter into act. Thus, in healing the doctor assists nature, which is the principal agent, by strengthening nature and prescribing medicines, which nature uses as instruments for healing. On the other hand, when something pre-exists only in passive potency, then it is the external agent which is the principal cause of the transition from potency to act. Thus, fire makes actual fire of air, which is potentially fire. Knowledge, therefore, pre-exists in the learner potentially, not, however, in the purely passive, but in the active, sense. Otherwise, man would not be able to acquire knowledge independently. Therefore, as there are two ways of being cured, that is, either through the activity of unaided nature or by nature with the aid of medicine, so also there are two ways of acquiring knowledge. In one way, natural reason by itself reaches knowledge of unknown things, and this way is called "discovery"; in the other way, when someone else aids the learner’s natural reason, and this is called "learning by instruction." In his autem quae fiunt a natura et arte eodem modo ars operatur et per eadem media quibus et natura: sicut enim natura in eo qui ex frigida causa laborat calefaciendo induceret sanitatem, ita et medicus; unde et ars dicitur imitari naturam; et similiter etiam contingit in scientiae acquisitione quod eodem modo docens alium ad scientiam ignotorum deducit, sicuti aliquis inveniendo deducit se ipsum in cognitionem ignoti. In effects which are produced by nature and by art, art operates in the same way and through the same means as nature. For, as nature heals one who is suffering from cold by warming him, so also does the doctor. Hence, art is said to imitate nature. A similar thing takes place in acquiring knowledge. For the teacher leads the pupil to knowledge of things he does not know in the same way that one directs himself through the process of discovering something he does not know. Processus autem rationis pervenientis ad cognitionem ignoti inveniendo est ut principia communia per se nota applicet ad determinatas materias et inde procedat in aliquas particulares conclusiones et ex his in alias; unde et secundum hoc unus alium dicitur docere quod istum decursum rationis, quem in se facit ratione naturali, alteri exponit per signa, et sic ratio naturalis discipuli per huiusmodi sibi proposita sicut per quaedam instrumenta pervenit in cognitionem ignotorum. Sicut igitur medicus dicitur causare sanitatem in infirmo natura operante, ita etiam homo dicitur causare scientiam in alio operatione rationis naturalis illius, et hoc est docere; unde unus homo alium docere dicitur et eius esse magister. Et secundum hoc dicit Philosophus 1 Posteriorum quod demonstratio est syllogismus faciens scire. Si autem aliquis alicui proponat ea quae in principiis per se notis non includuntur vel includi non manifestantur, non faciet in eo scientiam sed forte opinionem vel fidem, quamvis hoc etiam aliquo modo ex principiis innatis causetur: ex ipsis enim principiis per se notis considerat quod ea quae ex eis necessario consequuntur sunt certitudinaliter tenenda, quae vero eis sunt contraria, totaliter respuenda; aliis autem assensum praebere potest vel non praebere. Huiusmodi autem rationis lumen quo principia huiusmodi nobis sunt nota, est nobis a Deo inditum quasi quaedam similitudo increatae veritatis in nobis resultans. Unde cum omnis doctrina humana efficaciam habere non possit nisi ex virtute illius luminis, constat quod solus Deus est qui interius et principaliter docet, sicut natura interius et principaliter sanat; nihilominus homo et sanare et docere proprie dicitur modo praedicto. Now, in discovery, the procedure of anyone who arrives at the knowledge of something unknown is to apply general self-evident principles to certain definite matters, from these to proceed to particular conclusions, and from these to others. Consequently, one person is said to teach another inasmuch as, by signs, he manifests to that other the reasoning process which he himself goes through by his own natural reason. And thus, through the instrumentality, as it were, of what is told him, the natural reason of the pupil arrives at a knowledge of the things which he did not know. Therefore, just as the doctor is said to heal a patient through the activity of nature, so a man is said to cause knowledge in another through the activity of the learner’s own natural reason, and this is teaching. So, one is said to teach another and be his teacher. This is what the Philosopher means when he says: demonstration is a syllogism which makes someone know. But, if someone proposes to another things which are not included in self-evident principles, or does not make it clear that they are included, he will not cause knowledge in the other but, perhaps, opinion or faith, although even this is in some way caused by inborn first principles, for from these self-evident principles he realizes that what necessarily follows from them is to be held with certitude, and that what is contrary to them is to be rejected completely, and that assent may be given to or withheld from whatever neither follows necessarily from nor is contrary to self-evident principles. Now, the light of reason by which such principles are evident to us is implanted in us by God as a kind of reflected likeness in us of the uncreated truth. So, since all human teaching can be effective only in virtue of that light, it is obvious that God alone teaches interiorly and principally, just as nature alone heals interiorly and principally. Nevertheless, both to heal and to teach can still be used in a proper sense in the way we have explained. Ad primum igitur dicendum quod, quia Dominus praeceperat discipulis ne vocarentur magistri, ne posset intelligi hoc esse prohibitum absolute Glossa exponit qualiter haec prohibitio sit intelligenda: prohibemur enim hoc modo hominem vocare magistrum ut ei principalitatem magisterii attribuamus quae Deo competit, quasi in hominum sapientia spem ponentes et non magis de his quae ab homine audimus divinam veritatem consulentes quae in nobis loquitur per suae similitudinis impressionem qua de omnibus possumus iudicare. Reply Obj. 1: Since our Lord had ordered the disciples not to be called teachers, the Gloss explains how this prohibition is to be understood, lest it be taken absolutely. For we are forbidden to call man a teacher in this sense, that we attribute to him the pre-eminence of teaching, which belongs to God. It would be as if we put our hope in the wisdom of men, and did not rather consult divine truth about those things which we hear from man. And this divine truth speaks in us through the impression of its likeness, by means of which we can judge of all things. Ad secundum dicendum quod cognitio rerum in nobis non efficitur per cognitionem signorum sed per cognitionem aliarum rerum magis certarum, scilicet principiorum quae nobis per aliqua signa proponuntur et applicantur ad aliqua quae prius nobis erant ignota simpliciter, quamvis essent nobis nota secundum quid, ut dictum est; cognitio enim principiorum facit in nobis scientiam conclusionum, non cognitio signorum. Reply Obj. 2: Knowledge of things is not produced in us through knowledge of signs, but through knowledge of things more certain, namely, principles. The latter are proposed to us through signs and are applied to other things which were heretofore unknown to us simply, although they were known to us in some respect, as has been said. For knowledge of principles produces in us knowledge of conclusions; knowledge of signs does not. Ad tertium dicendum quod illa de quibus per signa edocemur cognoscimus quidem quantum ad aliquid et quantum ad aliquid ignoramus: utpote si doceamur quid est homo, oportet quod de eo praesciamus aliquid, scilicet rationem animalis vel substantiae aut saltem ipsius entis quae nobis ignota esse non potest; et similiter si doceamur aliquam conclusionem, oportet praescire de passione et subiecto quid sunt, etiam principiis per quae conclusio docetur praecognitis, omnis enim disciplina fit ex praeexistenti cognitione, ut dicitur in principio Posteriorum, unde ratio non sequitur. Reply Obj. 3: To some extent we know the things we are taught through signs, and to some extent. We do not know them. Thus, if we are taught what man is, we must know something about him beforehand, namely, the meaning of animal, or of substance, or at least of being itself, which last concept cannot escape us. Similarly, if we are taught a certain conclusion, we must know beforehand what the subject and predicate are. We must also have previous knowledge of the principles through which the conclusion is taught, for all teaching comes from pre-existing knowledge, as is said in the Posterior Analytics. Hence, the argument does not follow. Ad quartum dicendum quod ex sensibilibus signis quae in potentia sensitiva recipiuntur, intellectus accipit intentiones intelligibiles quibus utitur ad scientiam in se ipso faciendam: proximum enim scientiae effectivum non sunt signa sed ratio discurrens a principiis in conclusiones, ut dictum est. Reply Obj. 4: Our intellect derives intelligible likenesses from sensible signs which are received in the sensitive faculty, and it uses these intelligible forms to produce in itself scientific knowledge. For the signs are not the proximate efficient cause of knowledge, but reason is, in its passage from principles to conclusions, as has been said. Ad quintum dicendum quod in eo qui docetur scientia praeexistebat, non quidem in actu completo sed quasi in rationibus seminalibus, secundum quod universales conceptiones quarum cognitio est nobis naturaliter indita, sunt quasi semina quaedam omnium sequentium cognitorum; quamvis autem per virtutem creatam rationes seminales non hoc modo educantur in actum quasi ipsae per aliquam creatam virtutem infundantur, tamen id quod est in eis originaliter et virtualiter actione creatae virtutis in actum educi potest. Reply Obj. 5: In one who is taught, the knowledge did not exist in complete actuality, but, as it were, in seminal principles, in the sense that the universal concepts which we know naturally are, as it were, the seeds of all the knowledge which follows. But, although these seminal principles are not developed to actuality by any created power, as though they were infused by a created power, that which they have in a primitive way and virtually can develop into actuality by means of the activity of a created power. Ad sextum dicendum quod docens non dicitur transfundere scientiam in discipulum quasi illa eadem numero scientia quae est in magistro in discipulo fiat, sed quia per doctrinam fit in discipulo scientia similis ei quae est in magistro, educta de potentia in actum, ut dictum est. Reply Obj. 6: We do not say that a teacher communicates knowledge to the pupil, as though the knowledge which is in the teacher is numerically the same as that which arises in the pupil. It is rather that the knowledge which arises in the pupil through teaching is similar to that which is in the teacher, and this was raised from potency into act, as has been said. Ad septimum dicendum quod sicut medicus, quamvis exterius operetur, natura sola interius operante, dicitur facere sanitatem, ita et homo dicitur docere veritatem quamvis exterius annuntiet Deo interius docente. Reply Obj. 7: As the doctor is said to cause healing, although he works exteriorly, while nature alone works interiorly, so man is said to teach the truth, although he declares it exteriorly, while God teaches interiorly. Ad octavum dicendum quod Augustinus in libro De magistro per hoc quod probat solum Deum docere non intendit excludere quin homo exterius doceat, sed quod ipse solus Deus docet interius. Reply Obj. 8: When Augustine proves that only God teaches, he does not intend to exclude man from teaching exteriorly, but intends to say that God alone teaches interiorly. Ad nonum dicendum quod homo verus et vere doctor dici potest et veritatem docens et mentem quidem illuminans, non quasi lumen rationis infundens sed quasi lumen rationis coadiuvans ad scientiae perfectionem per ea quae exterius proponit, secundum quem modum dicitur Eph. 3:8–9 mihi autem omnium sanctorum minimo data est gratia haec illuminare omnes etc. Reply Obj. 9: Man can truly be called a true teacher inasmuch as he teaches the truth and enlightens the mind. This does not mean, however, that he endows the mind with light, but that, as it were, he co-operates with the light of reason by supplying external help to it to reach the perfection of knowledge. This is in accordance with Ephesians 3:8–9: to me, the least of all. the saints, is given this grace . . . to enlighten all men. Ad decimum dicendum quod duplex est sapientia, scilicet creata et increata, et utraque homini infundi dicitur et eius infusione homo mutari in melius proficiendo. Sapientia increata vero nullo modo mutabilis est, creata vero in nobis mutatur per accidens non per se; est enim ipsam considerare dupliciter: uno modo secundum respectum ad res aeternas de quibus est, et sic omnino immutabilis est. alio modo secundum esse quod habet in subiecto, et sic per accidens mutatur subiecto mutato de potentia habente sapientiam in actu habens: formae enim intelligibiles, ex quibus sapientia consistit, et sunt rerum similitudines et sunt formae perficientes intellectum. Reply Obj. 10: Wisdom is twofold, created and uncreated. Man is said to be endowed with both and to improve himself by advancing in them. Uncreated wisdom, however, cannot be changed in any way, whereas in us created wisdom can be changed for some extrinsic reason, though not by reason of anything intrinsic to it. We can consider this capacity for change in two ways. In one way, according to the relation which it has to eternal things, and in this way it is entirely unchangeable. In the other, according to the existence which it has in the subject, it is changed for some extrinsic reason when the subject which has wisdom in potency is changed into a subject having it in act. For the intelligible forms in which wisdom consists are both likenesses of things and forms perfecting the understanding. Ad undecimum dicendum quod in discipulo describuntur formae intelligibiles ex quibus scientia per doctrinam accepta constituitur, immediate quidem per intellectum agentem sed mediate per eum qui docet: proponit enim doctor rerum intelligibilium signa ex quibus intellectus agens accipit intentiones intelligibiles et describit eas in intellectu possibili; unde ipsa verba doctoris audita, vel visa in scripto, hoc modo se habent ad causandum scientiam in intellectu sicut res quae sunt extra animam quia ex utrisque intellectus agens intentiones intelligibiles accipit, quamvis verba doctoris propinquius se habeant ad causandum scientiam quam sensibilia extra animam existentia in quantum sunt signa intelligibilium intentionum. Reply Obj. 11: In the pupil, the intelligible forms of which knowledge received through teaching is constituted are caused directly by the agent intellect and mediately by the one who teaches. For the teacher sets before the pupil signs of intelligible things, and from these the agent intellect derives the intelligible likenesses and causes them to exist in the potential intellect. Hence, the words of the teacher, heard or seen in writing, have the same efficacy in causing knowledge as things which are outside the soul. For from both the agent intellect receives intelligible likenesses, although the words of the teacher are more proximately disposed to cause knowledge than things outside the soul, in so far as they are signs of intelligible forms. Ad duodecimum dicendum quod non est omnino simile de intellectu et visu corporali: visus enim corporalis non est vis collativa ut ex quibusdam suorum obiectorum in alia perveniat, sed omnia sua obiecta sunt ei visibilia quam cito ad illa convertitur; unde habens potentiam visivam se habet hoc modo ad omnia visibilia intuenda sicut habens habitum ad ea quae habitualiter scit consideranda, et ideo videns non indiget ab alio excitari ad videndum nisi quatenus per alium eius visus dirigitur in aliquod visibile, ut digito vel aliquo huiusmodi. Sed potentia intellectiva, cum sit vis collativa, ex quibusdam in alia devenit; unde non se habet aequaliter ad omnia intelligibilia consideranda, sed quaedam statim videt quae sunt per se nota, in quibus implicite continentur quaedam alia quae intelligere non potest nisi per officium rationis ea quae in principiis implicite continentur explicando; unde ad huiusmodi cognoscenda, antequam habitum habeat, non solum est in potentia accidentali sed etiam in potentia essentiali: indiget enim motore qui reducat eum in actum per doctrinam, ut dicitur in 8 Physicorum, quo non indiget ille qui iam aliquid habitualiter novit. Doctor ergo excitat intellectum ad sciendum illa quae docet sicut motor essentialis educens de potentia in actum, sed ostendens rem aliquam visui corporali, excitat eum sicut motor per accidens, prout etiam habens habitum scientiae potest excitari ad considerandum de aliquo. Reply Obj. 12: Intellectual and bodily sight are not alike, for bodily sight is not a power which compares, so that among its objects it can proceed from one to another. Rather, all the objects of this sight can be seen as soon as it turns to them. Consequently, anyone who has the power of sight can look at all visible things, just as one who has a habit of knowledge can turn his attention to the things which he knows habitually. Therefore, the seeing subject needs no stimulus from another to see something, unless, perhaps, someone else directs the subject’s attention to some object by pointing it out or doing something of the sort. But, since the intellective power can compare, it proceeds from some things to others. As a result, it does not have the same relation to all intelligible objects of consideration. Rather, the mind sees certain things immediately, those which are self-evident, in which are contained certain other things which it can understand only by using reason to unfold those things which are implicitly contained in principles. Thus, before the mind has the habit, it is not only in accidental potency to know these things, but also essential potency. For the mind needs a mover to actualize it through teaching, as is said in the Physics. But a man who already knew something habitually would not need this. Therefore, the teacher furnishes the pupil’s intellect with a stimulus to knowledge of the things which he teaches, as an indispensable mover, bringing the intellect from potentiality to actuality. But one who shows some thing to bodily sight prompts it to action as a nonessential mover. And one who has the habit of knowledge can in this way receive a stimulus from someone to consider something. Ad tertium decimum dicendum quod certitudo scientiae tota oritur ex certitudine principiorum: tunc enim conclusiones per certitudinem sciuntur quando resolvuntur in principia; et ideo hoc quod aliquid per certitudinem sciatur, est ex lumine rationis divinitus interius indito quo in nobis loquitur Deus, non autem ab homine exterius docente nisi quatenus conclusiones in principia resolvit nos docens, ex quo tamen nos certitudinem scientiae non acciperemus nisi inesset nobis certitudo principiorum in quae conclusiones resolvuntur. Reply Obj. 13: The whole certainty of scientific knowledge arises from the certainty of principles. For conclusions are known with certainty when they are reduced to the principles. Therefore, that something is known with certainty is due to the light of reason divinely implanted within us, by which God speaks within us. It comes from man, teaching from without, only in so far as, teaching us, he reduces conclusions to the principles. Nevertheless, we would not attain the certainty of scientific knowledge from this unless there were within us the certainty of the principles to which the conclusions are reduced. Ad quartum decimum dicendum quod homo exterius docens non influit lumen intelligibile sed est causa quodam modo speciei intelligibilis in quantum proponit nobis quaedam signa intelligibilium intentionum quas intellectus noster ab illis signis accipit et recondit in se ipso. Reply Obj. 14: Man, teaching from without, does not infuse the intelligible light, but he is in a certain sense a cause of the intelligible species, in so far as he offers us certain signs of intelligible likenesses, which our understanding receives from those signs and keeps within itself. Ad quintum decimum dicendum quod cum dicitur "nihil potest formare mentem nisi Deus", intelligitur de ultima eius forma sine qua informis reputatur quotcumque alias formas habeat; haec autem est forma illa qua ad Verbum convertitur et ei inhaeret per quam solam natura rationalis formata dicitur, ut patet per Augustinum Super Genesim ad litteram. Reply Obj. 15: When it is said that nothing but God can form the mind, this is understood of its basic form, without which mind would be considered formless, no matter what other forms it had. This is the form by which it turns toward the Word and clings to him. It is through this alone that rational nature is called formed, as is clear from Augustine. Ad sextum decimum dicendum quod culpa est in affectu in quem solus Deus imprimere potest, sicut infra patebit in sequenti articulo; ignorantia autem in intellectu est in quem etiam virtus creata potest imprimere, sicut intellectus agens imprimit species intelligibiles in intellectum possibilem quo mediante ex rebus sensibilibus et ex doctrina hominis causatur scientia in anima nostra, ut dictum est. Reply Obj. 16: Guilt is in the affections, on which only God can make an impression, as will appear later. But ignorance is in the understanding, on which even a created power can make an imprint. For the agent intellect impresses the intelligible species on the potential intellect, and through the mediation of this latter, scientific knowledge is caused in our soul by sensible things and by the teaching of man, as has been said. Ad septimum decimum dicendum quod certitudinem scientiae, ut dictum est, habet aliquis a solo Deo qui nobis lumen rationis indidit per quod principia cognoscimus ex quibus oritur scientiae certitudo; et tamen scientia ab homine etiam causatur in nobis quodam modo, ut dictum est. Reply Obj. 17: One has the certainty of scientific knowledge, as has been said, from God alone, who has given us the fight of reason, through which we know principles. It is from these that the certainty of scientific knowledge arises. Nevertheless, scientific knowledge can in a certain sense be caused in us by man, as has been said. Ad duodevicesimum dicendum quod discipulus ante locutionem magistri interrogatus responderet quidem de principiis per quae docetur, non autem de conclusionibus quas quis eum docet; unde principia non discit a magistro sed solum conclusiones. Reply Obj. 18: Before the teacher speaks, the pupil would, if asked, answer about the principles through which he is taught, but not about the conclusions which someone is teaching him. Hence, he does not learn the principles from the teacher, but only the conclusions. Articulus 2 Article 2 Utrum aliquis possit dici magister sui ipsius Whether one can be called his own teacher Secundo quaeritur utrum aliquis possit dici magister sui ipsius. Second, it is asked whether one can be called his own teacher? Et videtur quod sic quia actio magis debet attribui causae principali quam instrumentali; sed causa quasi principalis scientiae causatae in nobis est intellectus agens, homo autem qui docet exterius est causa quasi instrumentalis proponens intellectui agenti instrumenta quibus ad scientiam perducat; ergo intellectus agens magis docet quam homo exterius; si ergo propter locutionem exteriorem qui exterius loquitur dicitur magister illius qui audit, multo amplius propter lumen intellectus agentis ille qui audit dicendus est magister sui ipsius. Obj. 1: It seems that he can, for an activity should be ascribed more to the principal cause than to the instrumental cause. But in us the agent intellect is, as it were, the principal cause of the knowledge which is produced in us. But man who teaches another is, as it were, an instrumental cause, furnishing the agent intellect with the instruments by means of which it causes knowledge. Therefore, the agent intellect is more the teacher than another man. If, then, because of what a speaker says we call him the teacher of the one who hears him, the hearer should in a much fuller sense be called his own teacher because of the light of the agent intellect. Praeterea, nullus aliquid addiscit nisi secundum quod ad certitudinem cognitionis pervenit; sed certitudo cognitionis nobis inest per principia naturaliter nota in lumine intellectus agentis; ergo intellectui agenti praecipue convenit docere, et sic idem quod prius. Obj. 2: One learns something only in so far as he acquires certain knowledge. But such certitude is in us by reason of the principles which are naturally known in the light of the agent intellect. Therefore, the agent intellect is especially fitted to teach. We conclude as before. Praeterea, docere magis proprie convenit Deo quam homini, unde Matth. 23:8 unus est magister vester; sed Deus nos docet in quantum lumen nobis rationis tradit quo de omnibus possumus iudicare; ergo illi lumini actio docendi praecipue attribui debet, et sic idem quod prius. Obj. 3: To teach belongs more properly to God than to man. Hence, it is said in Matthew 23:8: for one is your master. But God teaches us in so far as he gives us the light of reason, by means of which we can judge about everything. Therefore, we should attribute the activity of teaching especially to that light. The same conclusion follows as before. Praeterea, scire aliquid per inventionem est perfectius quam ab alio discere, ut patet in 1 Ethicorum; si igitur ex illo modo acquirendi quo aliquis ab alio addiscit scientiam sumitur nomen magistri ut unus alterius sit magister, multo amplius ex modo accipiendi scientiam per inventionem debet accipi nomen magistri ut aliquis sui ipsius magister dicatur. Obj. 4: It is more perfect to learn something through discovery than to learn it from another, as is clear in the Ethics. If, therefore, a man is called a teacher in virtue of that manner of acquiring knowledge by which one learns from another so that the one is called the teacher of the other, he should with much greater reason be called a teacher in virtue of the process of acquiring knowledge through discovery, and so be called his own teacher. Praeterea, sicut aliquis inducitur ad virtutem ab alio et a se ipso, ita aliquis perducitur ad scientiam et per se ipsum inveniendo et ab alio addiscendo; sed illi qui ad opera virtutum perveniunt sine exteriori institutore vel legislatore dicuntur esse sibi ipsis lex, Rom. 2:14 cum gens quae legem non habent naturaliter quae legis sunt faciunt, ipsi sibi sunt lex; ergo et ille qui scientiam acquirit per se ipsum debet sibi ipsi dici magister. Obj. 5: Just as one is inspired to virtue by another and by himself, so also he gets to know something by discovering for himself and by learning from another. But those who attain to works of virtue without having another as an instructor or a lawgiver are said to be a law unto themselves, according to Romans 2:14: for when the Gentiles, who have not the law, do by nature those things that are of the law . . . they are a law to themselves. Therefore, the man who acquires knowledge by himself ought also to be called his own teacher. Praeterea, doctor est causa scientiae sicut medicus sanitatis, ut dictum est; sed medicus sanat se ipsum; ergo aliquis etiam potest se ipsum docere. Obj. 6: The teacher is a cause of knowledge as the doctor is a cause of health, as has been said. But a doctor heals himself. Therefore, one can also teach oneself. Sed contra est quod Philosophus dicit 8 Physicorum quod impossibile est quod docens addiscat quia docentem necesse est habere scientiam, discentem vero non habere; ergo non potest esse quod aliquis doceat se ipsum vel dici possit sui magister. On the contrary (1), the Philosopher says that it is impossible for one who is teaching to learn. For the teacher must have knowledge and the learner must not have it. Therefore, one cannot teach himself or be called his own teacher. Praeterea, magisterium importat relationem superpositionis sicut et dominus; sed huiusmodi relationes non possunt inesse alicui ad seipsum: non enim aliquis est pater sui ipsius aut dominus; ergo nec aliquis potest dici sui ipsius magister. Furthermore (2), the office of teacher implies a relation of superiority, just as dominion does. But relationships of this sort cannot exist between a person and himself. For one is not his own father or master. Therefore, neither can one be called his own teacher. Responsio. Dicendum quod absque dubio aliquis potest per lumen rationis sibi inditum absque exterioris doctrinae adminiculo devenire in cognitionem ignotorum multorum, sicut patet in omni eo qui per inventionem scientiam acquirit; et sic quodam modo aliquis est sibi ipsi causa sciendi, non tamen propter hoc proprie potest dici sui ipsius magister vel se ipsum docere. Duos enim modos principiorum agentium in rebus naturalibus invenimus, ut patet ex Philosopho in 7 Metaphysicae: quoddam enim est agens quod in se totum habet quod in effectu per eum causatur, vel eodem modo sicut est in agentibus univocis vel etiam eminentiori sicut est in agentibus aequivocis; quaedam vero agentia sunt in quibus eorum quae aguntur non praeexistit nisi pars, sicut motus causat sanitatem aut aliqua medicina calida in qua calor invenitur vel actualiter vel virtualiter, calor autem non est tota sanitas sed est pars sanitatis. In primis igitur agentibus est perfecta ratio actionis non autem in agentibus secundi modi, quia secundum hoc aliquid agit quod actu est, unde cum non sit in actu effectus inducendi nisi in parte, non erit perfecte agens. I answer that through the light of reason implanted in him and without the help of another’s instruction, one can undoubtedly acquire knowledge of many things which he does not know. This is clear with all those who acquire knowledge through discovery. Thus, in some sense one can be a cause of his own knowledge, but he cannot be called his own teacher or be said to teach himself. For in physical reality we find two types of active principles, as is clear from the Philosopher. Now, there is one type of agent which has within itself everything which it produces in the effect, and it has these perfections in the same way as the effect, as happens in univocal agents, or in a higher way than the effect, as in equivocal causes. Then, there is a certain type of agent in which there pre-exists only a part of the effect. An example of this type is a movement which causes health, or some warm medicine, in which warmth exists either actually or virtually. But warmth is not complete health, but a part of it. The first type of agent, therefore, possesses the complete nature of action. But those of the second type do not, for a thing acts in so far as it is in act. Hence, since it actually contains the effect to be produced only partially, it is not an agent in the perfect sense. Doctrina autem importat perfectam actionem scientiae in docente vel magistro; unde oportet quod ille qui docet vel magister est habeat scientiam quam in altero causat explicite et perfecte sicut in addiscente acquiritur per doctrinam. Quando autem alicui acquiritur scientia per principium intrinsecum, illud quod est causa agens scientiae non habet scientiam acquirendam nisi in parte, scilicet quantum ad rationes seminales scientiae quae sunt principia communia; et ideo ex tali causalitate non potest trahi nomen doctoris vel magistri proprie loquendo. But teaching implies the perfect activity of knowledge in the teacher or master. Hence, the teacher or master must have the knowledge which he causes in another explicitly and perfectly, as it is to be received in the one who is learning through instruction. When, however, knowledge is acquired by someone through an internal principle, that which is the active cause of the knowledge has the knowledge to be acquired only partially, that is, in the seminal principles of knowledge, which are the general principles. Therefore, properly speaking, we cannot call a man teacher or master because of such causality. Ad primum igitur dicendum quod intellectus agens, quamvis sit principalior causa quantum ad aliquid quam homo exterius docens, tamen in eo non praeexistit scientia complete sicut in docente, unde ratio non sequitur. Reply Obj. 1: Although to some extent the agent intellect is more the principal cause than another’s teaching, the knowledge does not pre-exist in it completely, as it does in the teacher. Hence, the argument does not follow. Ad secundum dicendum similiter sicut ad primum. Reply Obj. 2: A like solution should be given to the second difficulty.