Et sic diligenter consideranti apparet, quod nunquam in nobis aliquis motus apparet de novo, nisi praecedente aliquo alio motu. Et hoc promittit se in sequentibus magis manifestaturum. Thus, it is clear to anyone who considers the matter diligently that no motion ever newly appears in us unless some other motion preceded. And he promises to give a fuller explanation of this later. Lectio 5 Lecture 5 Dispositio rerum quantum ad motum et quietem qunique modis se habere potest excluduntur duo primi modi Things may be moved or at rest in five ways Principium autem considerationis est, quod quidem et dictae dubitationis, quare quaedam eorum quae sunt, aliquando quidem moventur, aliquando autem quiescunt iterum. Our enquiry will resolve itself at the outset into a consideration of the above-mentioned problem: what can be the reason that some things in the world at one time are in motion and at another are at rest again? Necesse autem aut omnia quiescere semper; aut omnia semper moveri; aut alia quidem moveri, alia autem quiescere. Now, one of three things must be true: either all things are always at rest, or all things are always in motion, or some things are in motion and others at rest. Et iterum horum aut quae moventur moveri semper, quae vero quiescunt quiescere semper; aut omnia apta nata sunt similiter moveri et quiescere; aut reliquum amplius et tertium est. Contingit enim alia quidem semper immobilia esse eorum quae sunt, alia vero semper moveri, alia autem cum utrisque accipere. In this last case again, either the things that are in motion are always in motion and the things that are at rest are always at rest, or they are all constituted so as to be capable alike of motion and of rest, or there is yet a third possibility remaining—it may be that some things in the world are always motionless, others always in motion, while others again admit of both conditions. Quod quidem nobis dicendum est: hoc enim habet solutiones omnium dubitatorum, et finis nobis est huius negotii. This last is the account of the matter that we must give, for herein lies the solution of all the difficulties raised and the conclusion of the investigation upon which we are engaged. Omnia igitur quiescere, et huius rationem quaerere dimittentes sensum, infirmitas quaedam est intellectus. To maintain that all things are at rest and to disregard sense perception in an attempt to show the theory to be reasonable would be an instance of intellectual weakness. Et de toto aliquo, sed non de parte ambiguitas est. Neque solum ad physicum, sed ad omnes scientias, ut ita dicam, et omnes opiniones; propter id quod motu utuntur omnes. It would call into question a whole system, not a particular detail; moreover, it would be an attack not only on the physicist, but on almost all sciences and all opinions, since motion plays a part in all of them. Amplius autem, de principiis importunitates sicut in rationibus circa doctrinas nihil sunt ad mathematicum, similiter autem in aliis: sic neque de eo quod nunc dicitur, ad physicum. Suppositio enim est quod natura principium motus sit. Further, just as in arguments about mathematics objections that involve first principles do not affect the mathematician—and similarly in the other sciences—so, too, objections involving the point that we have just raised do not affect the physicist, for it is a fundamental assumption with him that motion is ultimately referable to nature. Fere autem adhuc et omnia dicere moveri, falsum quidem, minus autem hoc praeter artem. Positum quidem enim est quod natura in physicis principium sit motus et quietis: similiter autem physicum est motus. The assertion that all things are in motion we may fairly regard as equally false, though it is less subversive of physical science. For though it was laid down in our course on physics that rest no less than motion is ultimately referable to nature herself, nevertheless motion is the characteristic fact of nature. Et dicunt quidam moveri eorum quae sunt, non alia quidem, alia vero non, sed omnia et semper; sed latere hoc nostrum sensum. Moreover, the view is actually held by some that not merely some things in the world are in motion and always in motion, but all things, though we cannot apprehend the fact by sense-perception. Ad quos etiam quidem non determinantes qualem motum dicunt, aut omnes, non difficile est contradicere. Although the supporters of this theory do not state clearly what kind of motion they mean, or whether they mean all kinds, it is no hard matter to reply to them. Neque enim augeri neque minui possibile est continue, sed est et medium. Thus we may point out that there cannot be a continuous process either of increase or of decrease: that which comes between the two has to be included. Est autem similis ratio huic de eo quod est guttam conterere, et nascentia lapides scindere. Non enim si tantum effodit aut removit gutta, et medium in medio tempore prius: The theory resembles that about the stone being worn away by the drop of water or split by plants growing out of it: if so much has been extruded or removed by the drop, it does not follow that half the amount has previously been extruded or removed in half the time. sed sicut navis tractus est, et guttae tot tantum movent, pars autem illarum in nullo tempore tantum. The case of the hauled ship is exactly comparable, for here we have so many drops setting so much in motion, but a part of them will not set as much in motion in any period of time. Dividitur enim quod remotum est in plura; sed nihil eorum motum est seorsum, sed simul. The amount removed is, it is true, divisible into a number of parts, but no one of these was set in motion separately: they were all set in motion together. Manifestum igitur quod non est necessarium semper aliquid abire, quia diminutio in infinita; sed totum aliquando abire. It is evident that, from the fact that the decrease is divisible into an infinite number of parts, it does not follow that some part must always be passing away; it all passes away at a particular moment. Similiter autem et in alteratione qualibet. Non enim si partibile in infinitum est quod alteratur, propter hoc et alteratio: sed velox fit multoties, sicut congelatio. Similarly, too, in the case of any alteration whatever, if that which suffers alteration is infinitely divisible, it does not follow from this that the same is true of the alteration itself, which often occurs all at once, as in freezing. Amplius, cum infirmetur aliquis, necesse est tempus fieri in quo sanabitur, et non in termino temporis mutari: necesse autem in sanitatem mutari, et in aliud nullum. Again, when any one has fallen ill, there must follow a period of time in which his restoration to health is in the future. The process of change cannot take place in an instant, yet the change cannot be a change to anything else but health. Quare dicere continue alterari, multum in manifestis est ambigere: in contrarium enim alteratio. The assertion that alteration is continuous is therefore an extravagant calling into question of the obvious: for alteration is a change from one contrary to another. Atque lapis neque durior fit neque mollior. Moreover, we notice that a stone becomes neither harder nor softer. Et secundum quod fertur, mirabile est si latuit lapis deorsum latus, aut manens in terra. Again, in the matter of locomotion, it would be a strange thing if a stone could be falling or resting on the ground without our being able to perceive the fact. Amplius autem, terra et aliorum unumquodque ex necessitate permanent quidem in propriis locis, moventur autem violenter ex his. Si igitur quaedam ipsorum sunt in propriis locis, necesse neque secundum locum omnia moveri. Quod igitur impossibile sit aut semper omnia moveri aut semper omnia quiescere, ex his et aliis huiusmodi sciet utique aliquis. Further, it is a law of nature that earth and all other bodies should remain in their proper places and be moved from them only by violence. Thus, from the fact that some of them are in their proper places, it follows that, in respect of place also, all things cannot be in motion. These and other similar arguments, then, should convince us that it is impossible either that all things are always in motion or that all things are always at rest. 1004. Postquam Philosophus in septimo ostenderat quod in moventibus et in mobilibus non est procedere in infinitum, sed est devenire ad aliquod primum; et hic iam ostendit quod motus semper fuit et semper erit; ulterius procedit ad inquirendum conditionem primi motus et primi motoris. 1004. Having shown in book 7 (242a15) that there is not an infinite process in movers and in mobiles, but that a first must be reached, and having now shown that motion has always been and always will be, the Philosopher goes on further to consider the condition of the first motion and of the first mover. Et dividitur in partes duas: And his treatment is divided into two parts. in prima ostendit quod primus motus est sempiternus, et quod primum movens est omnino immobile; In the first, he shows that the first motion is eternal and that the first mover is entirely immobile; secundo ex hoc procedit ad ostendendum qualis sit primus motus, et qualis sit primus motor, ibi: at vero aliud facientibus principium etc. second, he proceeds from this to show the condition of the first motion and of the first mover, at this matter will be (260a20; [1086]). Prima autem pars dividitur in partes tres: The first is divided into three parts: in prima ponit sub quaestione quandam divisionem quinquemembrem; in the first, he gives a division having five members; in secunda excludit tres partes propositae divisionis, ibi: omnia igitur quiescere etc.; in the second, he excludes three members of this division, at to maintain that (253a32; [1006]); tertio inquirit de duobus residuis membris, quod eorum sit verius, quia ex hoc dependet veritas quam inquirere intendit, ibi: omnia autem velle aliquando quidem etc. third, he investigates the two remaining members to see which of them is truer, because the truth of what he intends to settle depends on it at, we have now to take (254a15; [1016]). 1005. Dicit ergo primo quod principium sequentis considerationis, qua inquirere intendimus de primo motu et primo motore, est quod pertinet ad dubitationem praedictam (quam scilicet movit solvendo secundam rationem): unde contingit quod quaedam aliquando moventur, et aliquando quiescunt iterum, et non semper vel moventur vel quiescunt, ex quo ponitur motus sempiternus in communi? 1005. He says first (253a22), therefore, that the reason for the following consideration, in which we intend to investigate about the first motion and the first mover, is that it pertains to a question he raised in answering the second argument: it may be that some things in the world are always motionless, others always in motion, and are not either always in motion or always at rest, since motion in common is considered perpetual. Et dicit quod necesse est dispositionem rerum, quantum ad motum vel quietem, tripliciter se habere. And he says that the ways in which things are disposed with respect to motion or rest are necessarily limited to three. Quorum unus modus est, ut omnia semper quiescant, et nihil aliquando moveatur; The first of these is that all things be always at rest and nothing ever in motion; secundus modus est, ut omnia semper moveantur, et nihil quiescat; the second is that all things be always in motion and nothing at rest;