The question is whether place is a principle of generation in the way that a father is.

1 It appears that it is not:

For a father is a principle per se, whereas place is a principle per accidens, since it does not move.

2 Moreover, time is a principle of generation, since it is an extrinsic measure, as is place.

3 Porphyry speaks for the opposite view. ⁽¹⁾

4 One must say that the proposition is true if the similarity is understood with respect to the genus of cause, since both are in the genus of efficient cause; and this is how Porphyry understands the claim. That is why he says 'principle', which is uniquely suitable for the efficient cause. But the proposition is false if the similarity is understood with respect to the mode of the cause, since a father is efficient cause per se, whereas place is [an efficient cause that] merely contributes (coadiuvans) to generation and conserves the being of things. Now generation terminates at being. And an indication that place is a principle of generation is that lions are generated only in the second and third climate of the earth, and not in others. Similarly, certain plants bear fruit in some parts of the world, but if they were planted in another part of the world they would not bear fruit.

5 Hence the argument can be formulated like this: Something by means of which the power of the principal generator is received in the secondary generator is a principle of generation. This is how the supracelestial bodies are related to inferior bodies, "for man and the sun generate a man," according to Physics II [2, 194^b13]. For the secondary generator does not generate except through the power of the primary generator. Now place is something by means of which the power of the primary generator is received in every secondary generator. Therefore, etc.

6 One must notice, however, that place has a twofold nature. The first is its qualitative nature, by which it conserves and generates insofar as it receives some power that flows into it from the supracelestial bodies, which power is by nature apt to generate and conserve the placed body. And in this way the place in which we are is a principle of human beings and of other animals. Hence, on account of such power that has flowed into it, place can also be called an efficient cause.

Place also has a quantitative nature through which it contains [placed bodies], and in this way it is not a cause. The difference between these two is evident from Physics II [3, 195^a32-35] and Metaphysics V [2, 1013^b34-1014^a1].

7 The reply to the first argument [in n. 1] is evident.

8 To the second argument [in n. 2] I say that time does not contribute per se to generation nor does it save per se the thing generated. It is rather a cause of corruption per se, as is shown in Physics IV [12, 221^a30-^b8].

9 Note Physics IV: all things waste away and are corrupted in time. For time carries things away from the way they used to be. ⁽²⁾ For time is the number of motion, and in the number of motion is a successive corruption of the parts. Therefore, time does not contribute per se to generation.

1. Porphyry, Liber praedicabilium c. 'De genere'.

2. More literally, "For time makes a thing distant from the disposition in which it was."