1. A SPEECH, consisting of three propositions, from two of which the third follows, is called a SYLLOGISM; and that which follows is called the _conclusion_; the other two _premises_. For example, this speech, _every man is a living creature_, _every living creature is a body_, therefore, _every man is a body_, is a _syllogism_, because the third proposition follows from the two first; that is, if those be granted to be true, this must also be granted to be true. [Sidenote: In a syllogism there are but three terms.] 2. From two propositions which have not one term common, no conclusion can follow; and therefore no _syllogism_ can be made of them. For let any two premises, _a man is a living creature_, _a tree is a plant_, be both of them true, yet because it cannot be collected from them that _plant_ is the name of a _man_, or _man_ the name of a _plant_, it is not necessary that this conclusion, _a man is a plant_, should be true. Corollary: therefore, in the _premises_ of a _syllogism_ there can be but three _terms_. Besides, there can be no term in the _conclusion_, which was not in the _premises_. For let any two premises be, _a man is a living creature_, _a living creature is a body_, yet if any other term be put in the conclusion, as _man is two-footed_; though it be true, it cannot follow from the premises, because from them it cannot be collected, that the name _two-footed_ belongs to a _man_; and therefore, again, in every _syllogism_ there can be but three _terms_. [Sidenote: Major, minor and middle term; also major and minor proposition, what they are.] 3. Of these terms, that which is the _predicate_ in the conclusion, is commonly called the _major_; that which is the _subject_ in the conclusion, the _minor_, and the other is the _middle term_; as in this syllogism, _a man is a living creature_, _a living creature is a body_, therefore, _a man is a body_, _body_ is the _major_, _man_ the _minor_, and _living creature_ the _middle term_. Also of the premises, that in which the _major term_ is found, is called the _major proposition_, and that which has the _minor term_, the _minor proposition_. [Sidenote: The middle term in every syllogism to be determined in both propositions to one and the same thing.]