un-continued medium from the same class, as if C D and F (were assumed) of A B, but also from another (series). Thus, let A be to be changed, D to be moved, B to be delighted, and again G to be tranquillized. It is true then to predicate D of B and A of D, for whoever is delighted is moved, and what is moved is changed: again, it is true to predicate A of G, and G of B, for every one who is delighted is tranquillized, and he who is tranquillized is changed. Wherefore there is a syllogism through different media, and not from the same class, yet not so that neither is predicated of neither medium, since it is necessary that both should be present with something which is the same. We must also consider in how many ways there may be a syllogism of the same thing through the other figures.
Chapter 30
There is no science through demonstration of that which is fortuitous, since the fortuitous is neither as necessary nor as for the most part, but that which is produced besides these, and demonstration is of one of these. For every syllogism is through premises, either necessary, or through those which are for the most part (true), and if indeed the propositions are necessary, the conclusion also is necessary; but if for the most part (true), the conclusion also is of the same character. Hence if the fortuitous is neither as for the most part nor necessary, there cannot be demonstration of it.
Chapter 31
Neither is it possible to have scientific knowledge through sensation, for although there is
