I shall merely say, therefore, that, granting that some such term as 'Universe' or 'Being' may have no significant contradictory, if it stand for 'whatever can be perceived or thought of'; yet every term that stands for less than 'Universe' or 'Being' has, of course, a contradictory which denotes the rest of the universe.

And since every argument or train of thought is carried on within a special 'universe of discourse,' or under a certain _suppositio_, we may say that _within the given suppositio every term has a contradictory_, and that every predication concerning a term implies some predication concerning its contradictory.

But the name of the _suppositio_ itself has no contradictory, except with reference to a wider and inclusive _suppositio_.
The difficulty of actual reasoning, not with symbols, but about matters of fact, does not arise from the principles of Logic, but sometimes from the obscurity or complexity of the facts, sometimes from the ambiguity or clumsiness of language, sometimes from the deficiency of our own minds in penetration, tenacity and lucidity.

One must do one's best to study the facts, and not be too easily discouraged..