The logically primary step is thus not the separation of the physical and the psychical things plus the secondary demand to connect the physical things causally; the order is exactly opposite. The primary desire is to connect the real objects and to understand them as causes and effects. This understanding demands not only empirical observation, but insight into the necessary connection. Necessary connection, on the other hand, exists merely for identical objects and identical qualities. But in the various experiences only that is identical which is independent of the momentary individual experiences, and therefore we need as the ultimate aim a reconstruction of the object into the two parts, the one perceptional, which refers to our individual experience; and the other conceptional, which expresses that which can be conceived as identical in every new experience. The ideal of this constructed world is the mechanical universe in which every atom moves by causal necessity because there is nothing in that universe, no element of substance and no element of energy, which will not remain identical in all changes of the universe which are possibly to be expected. It becomes completely determinable by anticipation and the system of our submissions to the object can be completely constructed. The totality of intellectual efforts to reconstruct such a causally connected over-individual world of objects clearly represents a unity of its own. It is the system of physical sciences. The physical universe is thus not the totality of our objects. It is a substitution for our real objects, constructed by eliminating the individual parts of our objects of experience. These individual parts are the psychical aspects of our objective experience, and they clearly awake our scientific interest too. The physical sciences need thus as counterpart a division of mental sciences. Their aim must be the same. We want to foresee the psychical results and to understand causally the psychical experience. Yet it is clear that the plan of the mental sciences must be quite different in principle from that of the sciences of nature. The causal connection of the physical universe was ultimately anchored in the identity of the object through various experiences; while the object of experience was psychical for us just in so far as it could never be conceived as identical in different phases of reality. The psychical object is an ever new creation; my idea can never be your idea. Their meaning may be identical, but the psychical stuff, the content of my consciousness, can never be object for any one else, and even in myself the idea of to-day is never the idea of yesterday or to-morrow. But if there cannot be identity in different psychical experiences, it is logically impossible to connect them directly by necessity. If we yet want to master their successive appearance, we must substitute an indirect connection for the direct one, and must describe