which distinguishes us from them is reflective knowledge, the knowing
that we know.

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.