possibilities, is in another form as characteristic of Realism, and even in a sense of Mysticism, as it is of our own view of Being.
The discovery that the affirmation of reality is logically based upon the exclusion of the barely possible, is constantly made by common sense, is constantly illustrated by daily experience, and is popularly exemplified by that well-known destruction of possibilities which characterizes the passing of youth, the course of history, the reproduction of every species through relatively chance union of the members of that species, and by countless other instances. The Darwinian theory of the genesis of species by natural selection, is only a single instance of the application of this general concept that the real is a selection from amongst possibilities.
In elementary logic, as we earlier showed, it becomes manifest that all universal judgments are at once, as they say, negatively existential, and involve a destruction of logically possible classes of objects. Thus, let there be what the logicians call an Universe of Discourse, that is, a world of possible beings of which you are discoursing. Into that world let two classes of objects, A and B, be introduced. Then in your universe of discourse it becomes logically possible that there should be four subclasses of beings, namely, the things which are both A and B, the things which are A but not B, the things which are not A but which are B, and finally the things which are neither A nor B. Thus, for example, if your universe of discourse is to contain righteous men and happy men, there are possible the four sub-classes of men who are righteous and happy, who are righteous
