Man has debated at length and will continue to debate at length—­the world having been assigned as a theatre for his debates—­concerning the origin of knowledge; but, apart from the question as to what the real truth about this origin may be, which we will leave until later, it is a certainly ascertained fact that in the apparential order of things, in the life of beings who are endowed with a certain more or less cloudy faculty of knowing and perceiving, or who at any rate appear to act as if they were so endowed, knowledge is exhibited to us as bound up with the necessity of living and of procuring the wherewithal to maintain life.  It is a consequence of that very essence of being, which according to Spinoza consists in the effort to persist indefinitely in its own being.  Speaking in terms in which concreteness verges upon grossness, it may be said that the brain, in so far as its function is concerned, depends upon the stomach.  In beings which rank in the lowest scale of life, those actions which present the characteristics of will, those which appear to be connected with a more or less clear consciousness, are actions designed to procure nourishment for the being performing them.

Such then is what we may call the historical origin of knowledge, whatever may be its origin from another point of view.  Beings which appear to be endowed with perception, perceive in order to be able to live, and only perceive in so far as they require to do so in order to live.  But perhaps this stored-up knowledge, the utility in which it had its origin being exhausted, has come to constitute a fund of knowledge far exceeding that required for the bare necessities of living.

Thus we have, first, the necessity of knowing in order to live, and next, arising out of this, that other knowledge which we might call superfluous knowledge or knowledge de luxe, which may in its turn come to constitute a new necessity.  Curiosity, the so-called innate desire of knowing, only awakes and becomes operative after the necessity of knowing for the sake of living is satisfied; and although sometimes in the conditions under which the human race is actually living it may not so befall, but curiosity may prevail over necessity and knowledge over hunger, nevertheless the primordial fact is that curiosity sprang from the necessity of knowing in order to live, and this is the dead weight and gross matter carried in the matrix of science.  Aspiring to be knowledge for the sake of knowledge, to know the truth for the sake of the truth itself, science is forced by the necessities of life to turn aside and put it itself at their service.  While men believe themselves to be seeking truth for its own sake, they are in fact seeking life in truth.  The variations of science depend upon the variations of human needs, and men of science are wont to work, willingly or unwillingly, wittingly or unwittingly, in the service of the powerful or in that of a people that demands from them the confirmation of its own desires.