I must now again point out that it is an obstinate, scholastic misunderstanding not to be able to distinguish between a world-philosophy which is only psychological, and an extra-psychological theory, which concerns the objective thing. It is absolutely essential that the student of the results of the constructive method should be able to draw this distinction. In its first results the constructive method does not produce anything that could be called a scientific theory; it furnishes the _psychological lines of development_, a _path_ so to say. I must here refer the reader to my book, "Psychology of the Unconscious." The analytic reductive method has the advantage of being much simpler than the constructive method. The former reduces to well-known universal elements of an extremely simple nature. The latter has, with extremely complicated material, to construct the further path to some often unknown end. This obliges the psychologist to take full account of all those forces which are at work in the human mind. The reductive method strives to replace the religious and philosophical needs of man, by their more elementary components, following the principle of the "nothing but," as James so aptly calls it. But to _construct_ aright, we must accept the developed aspirations as indispensable components, essential elements, of spiritual growth. Such work extends far beyond empirical concepts but that is in accordance with the nature of the human soul which has never hitherto rested content with experience alone. Everything new in the human mind proceeds from speculation. Mental development proceeds by way of speculation, never by way of limitation to mere experience. I realise that my views are parallel with those of Bergson, and that in my book the concept of the libido which I have given, is a concept parallel to that of "élan vital"; my constructive method corresponds to Bergson's "intuitive method." I, however, confine myself to the psychological side and to practical work. When I first read Bergson a year and a half ago I discovered to my great pleasure everything which I had worked out practically, but expressed by him in consummate language and in a wonderfully clear philosophic style.