Intelligence has supplemented instinct and has guaranteed the survival of
the individual and of the race.

It has even protected man against himself, against the very dangers
arising out of his immunity from other dangers. A gregarious creature,
increasing and multiplying, he would be threatened with starvation did
not his intelligent control over nature furnish him with a food-supply
which makes it possible for vast numbers of human beings to live and
thrive on a territory of limited extent. Moreover, he has compassed those
complicated forms of social organization which reveal themselves in
cities and states, solving problems of production, transportation and
distribution before which undeveloped man would stand helpless.

And from the problem of living at all he has passed to that of living
well. He has created new wants and has satisfied them. He has built up
for himself a rich and diversified life, many of the activities of which
appear to have the remotest of bearings upon the mere struggle for
existence, but the exercise of which gives him satisfaction. Thus, the
primitive instinct of curiosity, once relatively aimless and
insignificant, has developed into the passion for systematic knowledge
and the persistent search for truth; the rudimentary aesthetic feeling
which is revealed in primitive man, and traces of which are recognizable
in creatures far lower in the scale, has blossomed out in those elaborate
creations, which, at an enormous expense of labor and ingenuity, have
come to enrich the domains of literature, music, painting, sculpture,
architecture. Civilized man is to a great extent occupied with the
production of what he does not need, if need be measured by what his
wants are at a lower stage of his development. But these same things he
needs imperatively, if we measure his need by his desires when they have
been multiplied and their scope indefinitely widened.