Page:Ferrier's Works Volume 1 - Institutes of Metaphysic (1875 ed.).djvu/481



If a thing is not this, it may be that; but if it is not this, and not that, it must be neither this nor that. (This is one of the strongest forms in which the law of contradiction, the criterion of all necessary truth, can be expressed.) Hence if absolute existence is not that which we know, it may be that which we are ignorant of; but if it is not that which we know, and not that which we are