If a traveler in Africa had to report a new animal species, he would not make special mention of the fact of its existence, because that is obvious. And though he were to relate things about the most abnormal existence, we should still know that this abnormality is only a deviation in degree which does not overstep the bounds of existence in general. But the human intellect is a greater novelty than the most wonderful animal species of the interior of Africa. You know my sharpwitted friend Englaender. When I told him that I was writing articles on the human mind, he advised me not to bother my head about it. He said that this was a subject no man knew anything about. And when the learned Mr. Hinze, whom you also know, wanted to prove the inevitability of religious faith and the inadequacy of all science, he always asked the pathetic question: What is consciousness? And he used to take on an expression, as if he had presented a book with seven seals. Now I don't want to class the professors of logic with such men. But it is a fact that the great multitude, among them many scientists, are quite unfamiliar with the truth that the existence of the blue sky and of the green trees is a uniform part of the same generality with the existence of our intellect. For this reason it is necessary to prove that the intellect exists in the same way that all other things do. For it is denied and misunderstood, not only by those who regard the spirit as a being of a transcendental nature, but also by those who admit the existence of the true contents of an ideological concept, but not of thought itself. In short, the matter is so obscure that I feel sure that you will likewise be as yet in doubt whether there are not two kinds of ideological concepts, one of them real, the other unreal. For two thousand years logic has proclaimed the sentence that thought is a form to be filled with real contents. True thought "must coincide with reality." It is true that there is a germ of sense in this statement, but it is misunderstood. The central point of logic is overlooked. Every thought must not only have a real content, but it is also necessary, in order to distinguish true thoughts or perceptions from untrue, to realize that thought is always and everywhere a part of reality and truth, even when it contains the most singular imaginations and errors.