In reply, I wish to say that the seeds sown by philosophy in the soil of science have long since blossomed and borne fruit. The product of history develops historically, grows and passes away, in order to live eternally in another form. The original deed, the original work, is fertile only in the contact with the conditions and relations of the time in which it is born. But it finally becomes an empty shell, when it has yielded its kernel to history. Whatever of a positive nature was produced by the science of the past, lives no longer in the words of the author, but has become more than spirit, has become flesh and blood in present science. In order, e. g., to know the products of physics and produce something new in its field, it is not necessary to first study the history of this science, nor derive the hitherto discovered laws from their fundamental source. On the contrary, historical research might only be an obstacle to the solution of a definite physical problem, for concentrated strength will naturally accomplish more than divided strength. In this sense, I consider my lack of other knowledge an advantage, because I am thus enabled to devote myself so much more intensely to my special object. I have striven hard to study this object and to learn everything which is known about it in my time. The history of philosophy has in a certain sense been repeated in the development of my individuality, since I speculated from my earliest youth on the means of satisfying my longing for a consistent and systematic conception of the world, and I believe I have finally found this satisfaction in the inductive understanding of the human faculty of thought. Note that it is not the faculty of thought in its various manifestations, not the different forms of it, but its general form, its general nature, that satisfied me and that I propose to discuss. My object is then very plain and circumscribed, indeed it is so simple, that I had difficulties in showing its nature from different points of view and was compelled to resort to numerous repetitions. At the same time, the question concerning the nature of the mind is a popular one, which is not limited to professional philosophy, but concerns all sciences. And whatever the history of science has contributed towards the solution of this question, must be generally alive in the scientific conceptions of the present. I could well be satisfied with this source.