There is however another point to be remembered in the consideration of Distribution of Terms of Propositions, which Brooks expresses as follows: "Distribution generally shows itself in the form of the expression, but sometimes it may be determined by the thought. Thus if we say, 'Men are mortal,' we mean _all men_, and the term men is distributed. But if we say 'Books are necessary to a library,' we mean, not 'all books' but 'some books.' The _test of distribution_ is whether the term applies to '_each and every_.' Thus when we say 'men are mortal,' it is true of each and every man that he is mortal." The Rules of Distribution of the Terms of Proposition are as follows: 1. All _universals_ distribute the _subject_. 2. All _particulars_ do not distribute the _subject_. 3. All _negatives_ distribute the _predicate_. 4. All _affirmatives_ do not distribute the _predicate_. The above rules are based upon logical reasoning. The reason for the first two rules is quite obvious, for when the subject is _universal_, it follows that the _whole subject_ is involved; when the subject is _particular_ it follows that _only a part_ of the subject is involved. In the case of the third rule, it will be seen that in every _negative_ proposition the _whole of the predicate_ must be denied the subject, as for instance, when we say: "Some _animals_ are _not horses_," the whole class of _horses_ is cut off from the subject, and is thus _distributed_. In the case of the fourth rule, we may readily see that in the affirmative proposition the whole of the predicate _is not denied_ the subject, as for instance, when we say that: "Horses are animals," we do not mean that horses are _all the animals_, but that they are merely a _part or portion_ of the class animal--therefore, the predicate, _animals_, is not distributed. In addition to the forms of Propositions given there is another class of Propositions known as _Definitive or Substitutive Propositions_, in which the Subject and the Predicate are exactly alike in extent and rank. For instance, in the proposition, "A _triangle_ is a _polygon of three sides_" the two terms are interchangeable; that is, may be substituted for each other. Hence the term "substitutive." The term "definitive" arises from the fact that the respective terms of this kind of a proposition necessarily _define_ each other. All logical definitions are expressed in this last mentioned form of proposition, for in such cases the subject and the predicate are precisely equal to each other. CHAPTER X. IMMEDIATE REASONING In the process of Judgment we must compare two concepts and ascertain their agreement of disagreement. In the process of Reasoning we follow a similar method and compare two judgments, the result of such comparison being the deduction of a third judgment.