From two particular propositions nothing can be concluded.
5. And therefore of two premises, in both which the middle term is particular, a syllogism cannot be made; for whether the middle term be the subject in both the premises, or the predicate in both, or the subject in one, and the predicate in the other, it will not be necessarily determined to the same thing. For let the premises be,
| Some man is blind, |  | In both which the middle |
| Some man is learned, | term is the subject, |
it will not follow that blind is the name of any learned man, or learned the name of any blind man, seeing the name learned does not contain the name blind, nor this that; and therefore it is not necessary that both should be names of the same man. So from these premises,
| Every man is a living-creature, | | In both which the middle |
| Every horse is a living-creature, | term is the predicate, |
nothing will follow. For seeing living creature is in both of them indefinite, which is equivalent to particular, and that man may be one kind of living creature, and horse another kind, it is not necessary that man should be the name of horse, or horse of man. Or if the premises be,
| Every man is a living-creature, Some living creature is four-footed, |  | In one of which the middle-term |
| is the subject, and in the | ||
| other the predicate, |
the conclusion will not follow, because the name living creature being not determined, it may in one of them be understood of man, in the other of not-man.
A syllogism is the collection of two propositions into one sum.
6. Now it is manifest from what has been said, that a syllogism is nothing but a collection of the sum of two propositions, joined together by a common term, which is called the middle term. And as proposition is the addition of two names, so syllogism is the adding together of three.