real life shows man in so many relations, so closely implicated with his environment, that he can strive for nothing for himself without also striving for others. This extension of interests has no limits; there is nothing in the whole of infinity which could not in this way become to man, indirectly, a means of self-preservation and thus an object of desire. The naturalistic type of life extends from the most general of impulses to every branch of activity, and forms every department of life in a distinctive fashion. Knowledge depends entirely upon experience; every speculative element must be excluded as a subjective delusion; in all its branches knowledge is nothing else than a broadened Natural Science. Art may not pursue imaginary ideals; it finds its single task in the faithful and simple reproduction of the natural environment. Social life and endeavour will develop, above all, natural powers, and will seek to adapt itself to the conditions given by nature, and, rejecting all aims based upon mere imagination, it will care chiefly for the physical welfare of the whole, as the source of all power and of all success. It is not difficult to understand how this form of life was able to win and carry away the minds of its contemporaries. In the first place it has the character of simplicity and immediacy, which, in contrast with the complexity and the remoteness of the traditional position, appears a great advantage. For, in this scheme, life, with all its multiplicity, is dominated and unified by the idea of natural self-preservation; and the things which immediately affect us, which lie physically and psychically near to us, come most directly into relation to this aim. It is a further tendency of this scheme of life to bring the whole of existence into a state of activity and restless advance. For the state of conflict which prevails under the naturalistic system allows nothing to persist merely because of its present existence or through the weight of tradition, but everything must always be reasserting its right to existence; it must stretch and extend itself in order to be useful in the life of the present. That which cannot satisfy this test is unmercifully thrown over as a dead weight. It is also of great importance to the theory in question that nature and the world are involved in ceaseless change, and that, along with the conditions of life, the requirements also alter: the matter is one of continually accommodating oneself anew; and so life is placed entirely in the present, and the fixity of an absolute conception and treatment of change yields to the instability of a relative one. Last of all, and most especially, life according to its own conviction bears the character of truth. For human striving appears to attain the firm basis of reality, and to become truthful in itself only when it is definitely related to the surrounding world; while, so long as it trusted to the