there be C, hence there may be many causes of the same of the same thing, but not to the same in species, for instance, the cause why quadrupeds are long-lived, is their not having bile, but why birds live long, their being of a dry complexion, or something else: if however they do not arrive immediately at an individual, and there is not one medium only, but many, the causes also are many.
Chapter 18
Which of the media is the cause to singulars, whether that which belongs to the first universal, or that to the singular? Evidently the nearest to the singular to which it is cause. For this is the cause why the first, under the universal, is inherent, C is the cause that B is inherent in D, hence C is the cause why A is inherent in D, but B is the cause why it is in C, yet to this itself is the cause.
Chapter 19
Concerning syllogism then and demonstration, what either of them is, and how it is produced, is clear, and at the same time about demonstrative science, for it is the same: but about principles, how they become
