Book II, lectio XIQUOMODO PER DEMONSTRATIONEM ACCIPIATUR CAUSA QUAE NON EST SIMUL CUM EFFECTU

Speculandum igitur quid est continens ut post id quod factum est, sit fieri in rebus. Aut manifestum est quod non est habitum cum facto esse quod fit; neque enim factum cum post facto esse: termini enim sunt et atomi. Sicut igitur neque puncta ad invicem sunt habita, neque quae facta sunt, utraque enim indivisibilia sunt; neque igitur quod fit cum eo quod factum est propter idem; quod quidem enim fit divisibile est, quod autem factum est indivisibile est. Sicut igitur linea ad punctum se habet, sic id quod fit ad quod factum est; sunt enim infinita facta in eo quod fit. Magis autem manifestum in universalibus de motu oportet dicere de his.

De hoc quidem igitur quomodo cum eo quod consequenter fit generatione, se habeat media causa, in tantum acceptum sit; necesse enim et in iis mediam et primam sine medio esse; ut A factum est, quoniam C factum est, posterius autem C factum, A autem prius. Principium igitur est C propter id quod proximum est ipsi nunc, quod est principium temporis; sed C factum est quoniam D factum est; D igitur cum factum est, A necesse est factum esse. Causa autem est C: D enim facto necesse est C factum esse, C autem facto necesse est A prius fuisse. Sic autem accipiens aliquod medium stabit alicubi immediatum. Aut semper intercedet propter infinitum? Non enim contiguum factum cum facto, quemadmodum dictum est. Sed incipere tamen necesse est a medio et ab ipso nunc primo.

Similiter autem est et in eo quod erit. Si enim verum est dicere quoniam erit D, necesse est prius verum dicere quoniam A erit; huius autem causa est C; si quidem enim D erit, prius C erit, si vero C erit, prius A erit. Similiter autem est decisio infinita et in iis; non enim sunt talia quae erunt contigua ad invicem; principium autem et in iis immediatum sine medio accipiendum est.

Habet autem sic se et in operibus. Si facta est domus, necesse est decisos esse lapides: et factum esse hoc propter quid? quoniam necesse est fundamentum factum esse si domus facta est; si vero fundamentum est, prius lapides esse factos necesse est. Iterum si erit domus, similiter prius erunt lapides; demonstratur autem per medium similiter; erit enim fundamentum prius.

The Latin version St Thomas commented, as the Leonine edition prints it.

The cause of things which are, is the same also as that of things which are generated, which have been generated, and which will be, for the middle is the cause, except that being is the cause to be, what is generated, to those which are generated, what has been, to those which have been, and what will be to those that will be. Thus why was there an eclipse? because the earth was interposed, but an eclipse is generated, because an interposition of the earth is generated, but there will be, because the earth will be, and there is, because it is interposed. What is ice? Let it be assumed to be congealed water; let water be C, congealed A, the middle cause B, a perfect defect of heat; B then is present with C, but with this A, viz. to be congealed, but ice is generated, when B is generated, it was so, when the latter was so, and it will be, when the latter will be.

Hence that which is thus a cause, and that of which it is the cause, are generated at one and the same time, when they are generated; are simultaneously when they are; and in like manner, in respect to the having been, and the will be, generated. In the case of things which are not simultaneous, are there in a continued time, as it seems to us, different causes of different things? for instance, is another thing having been generated the cause of this thing having been generated, and another thing which will be, the cause that this will be, and of this being, something which was generated before? the syllogism however is from what was afterwards generated. And the principle of these are those things which have been generated, wherefore the case is the same as to things which are generated. From the prior indeed there is no (syllogism), as that this thing was afterwards generated, because that thing was generated, it is the same also in regard to the future. For whether the time be indefinite or definite, it will not result that because that thing was truly said to have been generated, this which is posterior is truly said to have been generated, since in the interval it will be false to say this,¹ when already another thing² has been produced. The same reasoning also happens to what will be, nor because that³ was produced, will this be, as the middle must be generated at the same time;⁴ of things that have been that which has been, of the future the future, of what are produced that which is produced, of things which are that which is, but of what was generated, and of that which will be, the middle cannot possibly be produced at one and the same time. Moreover neither can the interval § be indefinite, nor definite,⁵ since it will be false to assert it in the interval;⁶ but we must consider what is connected with it, so that after the having been generated, to be generated may exist in things.⁷ Or is it evident that what is generated is not connected with what was generated ? for the past does not cohere with what was generated, since they are terms and individuals. As then neither points are mutually connected, those things which have been produced are not so, for both are indivisible; nor for the same reason does that which is, cohere with that which has been generated, for that which is generated is divisible, but that which has been is indivisible. As a line then is to a point, so is that which is to that which was generated, for infinite things which have been, are inherent in that which is;|| we must however enunciate these matters more clearly in the universal discussions about motion. Concerning then the manner in which, when there is a successive generation, the middle cause subsists, let so much be assumed, for in these also it is necessary that the middle and the first should be immediate, thus A was generated because C was so, but C was after, A before. The principle indeed is C, because it is nearer to the now, which is the principle of time, but C was generated if D was, hence from D having been, it is necessary that A should have been. The cause however is C, for from D having been, it is necessary that C should have been generated, but C having been, A must of necessity have been produced before. When however we thus assume the middle, will (the process) at any time stop at the immediate, or on account of the infinity will a medium always intervene? for, as we have stated, what has been generated is not connected with what has been; nevertheless we must commence at least from the immediate⁸ and from the first now.⁹ Likewise with regard to the “will be,” for if it is true to say that D will be, it is necessary that, prior to this, it should be true to say that A will be, the cause however of this is C, for if D will be, prior to it C will be, but if C will be, prior to it A will be. Likewise also in these the division is infinite, for things which will be, are not mutually coherent, but an immediate principle must also be assumed in these. It is thus in the case of works, if a house has been built, stones must necessarily have been cut, and formed; and why this? because the foundation must of necessity have been laid, if the house was built, but if the foundation was laid, stones must necessarily have been prepared before. Again, if there shall be a house, in like manner there will be stones prior to this, still the demonstration is in like manner through a medium, for the foundation will have a prior subsistence.

Notwithstanding, since we see in things which are, that there is a certain generation in a circle, this happens when the middle and the extremes follow each other, for in these there is a reciprocation; this however was shown in the first treatise, viz. that the conclusions are converted; but the case of being in a circle is thus. In works it appears after this manner, when the earth has been moistened, vapour is necessarily produced, from the production of this, there is a cloud, from this last, water, and from the presence of this, the earth is necessarily moistened, this however was the (cause) at first, so that it has come round in a circle, for any one of these existing, another is, and if that is, another, and from this, the first.

There are some things which are generated universally, (for always, and in every thing, they either thus subsist, or are generated,) but others not always, but for the most part; thus not every vigorous man has a beard, but this is generally the case, now of such things it is necessary that the medium also should be for the most part; for if A is universally predicated of B, and this of C universally, it is necessary that A also should be predicated always, and of every C, (for the universal is that which is present with every individual and always,) but it was supposed to be for the most part, wherefore it is necessary that the medium also, B, should be for the most part: hence of those which are for the most part, the principles are immediate, as many as thus subsist for the most part, or are generated.

The whole chapters, in the translation of Octavius Freire Owen (London: George Bell & Sons, 1889 (Bohn's Classical Library), vol. I, from the plates of the first edition (London: H. G. Bohn, 1853), same pagination).