Naturalism denies all independence of the spiritual life, which it regards as nothing more than an adjunct to the realm of nature, and one that can only exist along with sense existence, as a part of or as a supplement to it. Spirituality has, therefore, to subordinate itself and conform entirely to the life of nature; it can never produce and guide a movement from itself, never evolve a basal and comprehensive activity, never withdraw itself into its own sphere as into an independent realm. All self-existent spirituality fades to a world of mere shadows; whatever makes itself felt in us can only become a complete reality by winning flesh and blood through the appropriation of physical forces. Life, thus understood, possesses nothing in itself; it receives everything from its relations to the environment with which it is bound up: thought brings forth no new ideas; all ideas are merely abbreviations of sense impressions. Effort can never realise purely spiritual values; the essence of all happiness is sensuous enjoyment, however refined that may in some cases be. The naturalistic system of life receives a more definite delineation from the representation of nature, which the mechanical theory, together with a theory of descent adapted to it, sketches and impressively holds up to the present age. By this theory nature is completely resolved into a co-existence of individual forces, which, within the narrow bounds of existence, must clash violently together, and assert themselves one against the other in ceaseless conflict. This conflict, however, is a source of progressive movement, in that it brings together, establishes, and employs everything useful for self-preservation; it keeps life in a state of youthful freshness, in that new conditions continually arise and demand new accommodations with respect to the biologico-economic environment. A biologico-economic mode of thought is evolved which revolutionises all previous estimations of values. Everything intrinsically valuable disappears from the world; its expulsion seems a deliverance from a confused, indeed a meaningless, conception of things; the useful, that which promotes the interests of living beings, each after its kind, in the struggle for existence, becomes the all-dominating value. No mysterious being of things is apprehended in the True; but those presentations and systems of thought are called true which ensure that the best accommodation to the conditions of life shall be attained, and which just in this way hold the individuals together. No longer does a Good speak to man with austere demand from a transcendent sovereignty; but that is good which, within our experience, is of service to the preservation of life. The Beautiful, also, is subordinated to the useful, and it is solely by its value in relation to this that it asserts itself. In everything, it is only one's own welfare, the interest of individual preservation, that directly inspires conduct; but