Enough has now been said to show the basis on which rests the whole superstructure, of man's mental attitude toward the cosmos. Despite all uncertainties regarding the details of the process, we may be assured of its fundamental nature, and are thus compelled to recognize the dependence of the forms of man's mental attitude toward the universe upon his knowledge of himself. It is because his own actions have their source in a personal will that he refers external movements to will. He is conscious of his own acts, and the world around him can not be devoid of a like illumination. Does he himself plan? Nature must also be intelligent. And the highest qualities which he can discover in himself he reads unhesitatingly into the cosmos.
At first sight, then, knowledge may seem inextricably involved in the process here described. If man can not know the external system to which he must adapt himself save by assimilating it to himself--save by interpreting it on the basis of analogies which he discovers between his own body and its activities, and the world with its activities--are we not committed by our very nature as organisms to all the errors which that nature imposes upon us? If, in other words, every effort to view the universe as it is, independently of us, be rendered impossible by the very nature of the knowing process, with what chance of success shall we seek to eliminate those vitalistic and psychomorphic characters which seem to belong to that process as its very warp and woof? In reality our knowledge inflicts upon us no such dilemma. Man is the helpless "measure of the universe" only to the extent that his reasoning processes are undeveloped. That knowledge must always have a subjective element is undoubted, but that man must always mistake the subjective vesture with which things are clothed by the senses for the things themselves is an inference which the whole history of thought negatives. While his life remained simple, primitive man could regard appearances as realities without prejudicing the overplus of utility brought to him by his knowledge. Yet as his relation to the natural surroundings grew in complexity, the importance of the reasoning process, with its veto power over the deliverances of the senses, began to assert itself. At first accepted with little or no demur, these deliverances came more and more to be challenged in the interest of self-maintenance; and finally, by expansion of a germ possessed by the mind in the beginning, there was developed that way of dealing with the testimony of appearances which we call the objective method. The evidence previously accepted had been, though on the whole useful, in large measure misleading. For in appearances men saw and felt mainly what Nature was for them, and only to a minor degree what the external world was for and in itself. The great need of the investigator of Nature is to know what things are independently of man, in order to know how they act on one another, as a means of knowing how they will act on the human organism, and how that organism may react on them in the interest of its own life. The prejudice done by implicit reliance on sense testimony arose out of the fact that it presented objects as largely unrelated to each other--as so much being, rather than as so much doing, acting and interacting, determining and interdetermining. It became the function of reason to develop, out of the material furnished by the senses, a knowledge of the true nature of the system external to man and involving him in its scope which we call universe. In the carrying out of this function the analogical process has remained, but the analogies utilized, from being likenesses between what things seem to be to the senses, have more and more become analogies between propositions made regarding what things do, regarding how things act upon, are related to and determine each other.