=3. The Aim of Science.=These views are deliberately opposed to a very widespread idea that science should be cultivated "for its own sake," and not for the sake of the benefits it actually brings or may be made to bring. We reply that there is nothing at all which is done merely "for its own sake." Everything, without exception, is done for human purposes. These purposes range from momentary personal satisfaction to the most comprehensive social services involving disregard of one's own person. But in all our actions we never get beyond the sphere of the human. If, therefore, the phrase "for its own sake" means anything, it means that science should be followed for the sake of the immediate pleasure it affords, that is to say, as _play_ (as we have just characterized it), and in the "for-its-own-sake" demand there is hidden a misunderstood idealism, which, on closer inspection, resolves itself into its very opposite, the degradation of science. The element of truth hidden in that misunderstood phrase is, that in a higher state of culture it is found better to disregard the _immediate_ technical application in the pursuit of science, and to aim only for the greatest possible perfection and depth in the solution of its individual problems. Whether this is the correct method of procedure and when it is so, is solely a question of the general state of culture. In the early stages of human civilization such a demand is utterly meaningless, and all science is necessarily and naturally confined to immediate life. But the wider and more complex human relations become, the wider and surer must the ability to predict future events become. Then it is the function of prophesying science to have answers ready for questions which as yet have not become pressing, but which with further development may sooner or later become so. In the net-like interlacing of the sciences, that is, of the various fields of knowledge, described in the introduction, we must always reckon with the fact that our anticipation of what kind of knowledge we shall next need must always remain very incomplete. It is possible to foresee future needs in general outline with more or less certainty, but it is impossible to be prepared for particular individual cases which lie on the _border line_ of such anticipation, and which may sometimes become of the utmost importance and urgency. Therefore it is one of the most important functions of science to achieve as _perfect_ an elaboration as possible of _all_ the relations conceivable, and in this practical necessity lies the foundation of the general or _theoretical_ elaboration of science.