The teacher who, because of his lofty mission, claims the right of forming souls, of arousing those powerful moral energies which alone empower man to live as a human being, may not, must not be ignorant of the fact that the contention of naturalism, which makes of the world an abstract reality, presupposed by the human spirit and therefore anterior and indifferent to it, is a belief that has been superseded and surpassed by modern thought. The teacher too can easily grasp this view, for in gathering all the arguments by which, along different lines, the new conception of reality has been attained, we find that the whole matter reduces itself to a simple and very easy reflection. Very easy in itself, though it may seem difficult to the greater part of us,--to the superficial thinkers, to the absent-minded, to those who lack the strength necessary to face the great responsibility imposed upon us by the truth which is derived from this reflection. For naturalism reduces itself to the affirmation that we think nature, but do not ourselves exist; nature alone exists. We do not exist and yet we think, and we think of nature as existing. We do not exist and yet nature exists, of whose existence we have no other testimony than our thoughts. And if thought is a shadow, what will reality then be? The "dream of a shadow," in the words of the Greek poet. Is it possible for us to stop at this conclusion? Is it possible for an inexistent thing to vouch for the existence of something which we know only from its attestations? Such is the absurd position we are forced into when we assume that Thought, in equipoise with reality, remains outside of it and leaves it out of its own self.