De Iudiciis Astrorum
On Astrology
Quia petisti ut tibi scriberem an liceret iudiciis astrorum uti, tuae petitioni satisfacere uolens, super ea quae a sacris doctoribus traduntur, scribere curaui.
Because you requested that I write to you about whether it is right to engage in astrology, and since I wanted to address your question adequately, I took time to collect the teachings handed down by the sacred doctors concerning this question.
In primis ergo oportet te scire quod uirtus celestium corporum ad immutanda inferiora corpora se extendit. Dicit enim Augustinus V De ciuitate Dei Non usquequaque absurde dici potest ad solas corporum differentias afflatus quosdam sydereos peruenire. Et ideo, si aliquis iudiciis astrorum utatur ad prenoscendum corporales effectus, puta tempestatem et serenitatem aeris, sanitatem uel infirmitatem corporis, uel ubertatem et sterilitatem fructuum, et cetera huiusmodi que ex corporalibus et naturalibus causis dependent, nullum uidetur esse peccatum. Nam omnes homines circa huiusmodi effectus aliqua obseruatione utuntur celestium corporum: sicut agricole seminant et metunt certo tempore quod obseruatur secundum motum solis; naute nauigationes uitant in plenilunio, uel in lune defectu; medici circa egritudines creticos dies obseruant, qui determinantur secundum cursum solis et lune. Vnde non est inconueniens, secundum aliquas alias occultiores obseruationes stellarum, circa corporales effectus uti astrorum iudicio.
You should know, first of all, that the power of celestial bodies extends to the changeable bodies below them. As Augustine says: it is not wholly absurd to say that certain celestial influences are able to cause differences only in bodies (De civitate Dei v, 6). Therefore, if someone should use horoscopes for predicting bodily effects, such as storms or calm weather, the health or sickness of a body, or the abundance or sterility of crops, and similar things which depend on bodily and natural causes, in these cases the use of astrology does not appear to be sinful. For to some extent all men make use of the observation of celestial bodies. Farmers, for instance, sow and reap at certain times that are determined by the motion of the sun; sailors avoid journeying both during the full moon, and also during lunar eclipses; in the treatment of ailments, doctors observe critical days, which they determine according to the influence of the sun and the moon. For this reason, it is not unfitting to use astrology to determine bodily effects according to other more obscure observations of the stars.
Hoc autem omnino tenere oportet, quod uoluntas hominis non est subiecta necessitati astrorum; alioquin periret liberum arbitrium, quo sublato non deputarentur homini neque bona opera ad meritum, neque mala ad culpam. Et ideo certissime tenendum est cuilibet christiano, quod ea que ex uoluntate hominis dependent, qualia sunt omnia humana opera, non ex necessitate astris subduntur; et ideo dicitur Ier. x A signis celi nolite metuere que gentes timent.
Nevertheless, we ought to hold firmly that the will of man is not subject to the necessity of the stars. Otherwise, it would do away with free will; and if free will were taken away, good works would not be assigned to men for their merit, nor evil works for their fault. For this reason, all Christians should with utmost certainty hold that things which depend on the will of man, such as all human works, are not by necessity subject to the stars. Therefore, it is written: do not be terrified by the signs of heaven, which the nations fear (Jer 10:2).
Sed dyabolus, ut omnes pertrahat in errorem, immiscet se operibus eorum qui iudiciis astrorum intendunt ; et ideo Augustinus dicit in II Super Genesim ad litteram Fatendum, quando ab astrologis uera dicuntur, instinctu quodam occultissimo dici, quem nescientes humane mentes patiuntur ; quod cum ad decipiendos homines fit, spirituum immundorum et seductorum operatio est, quibus quedam uera de temporalibus rebus nosse permittitur. Et ideo Augustinus dicit in II De doctrina christiana quod huiusmodi obseruationes astrorum referende sunt ad quedam pacta cum demonibus habita. Est autem omnino christiano uitandum pactum uel societatem cum demonibus habere, secundum illud Apostoli I Cor. x Nolo uos fieri socios demoniorum. Et ideo pro certo tenendum est graue peccatum esse, circa ea que a uoluntate hominis dependent iudicio astrorum uti.
But in order to draw all men into error, the Devil mingles himself into the activities of those who eagerly consult astrology. Therefore, Augustine remarks: we must admit that when the truth is spoken by astrologers, it is revealed by a certain very occult prompting, to which the human mind is subject without knowing it. And since it happens in order to deceive men, it is the work of unclean and lying spirits who are permitted knowledge of certain truths concerning temporal things (De Genesi ad litteram ii, 15). Consequently, Augustine says (De doctrina Christiana ii, 23) that such observations should be attributed to certain pacts entered into with demons. Keeping pacts and communion with demons should be entirely avoided by Christians, as the Apostle says: I do not wish you to be allies to demons (1 Cor 10:20). Therefore, it should be resolutely held that it is a grave sin to engage in astrology concerning those things which depend on the will of man.