IN the lectures preceding this one we have seen that
the universe comes to life as time passes; life ap-
pears in a lifeless world. Life changes, develops;
breaks into streams that diverge in all directions;
some moving to destruction while others progress
toward higher conditions. Look now at certain prob-
lems in the management of life; problems common to
our own life and to that of other organisms. Here we
come upon the immediate bearing of biological knowl-
edge upon conduct.

The success of organisms--their survival and effi-
ciency, the fulness of their lives--depends not alone
on their structure and inner physiological processes;
it depends in large measure on the way they behave.
It depends on their maintaining proper relations with
the rest of the world. Life is a complex set of orderly
processes, enveloped in a world of conflicting, clash-
ing conditions and agents. Many conditions, many
processes, in this outer world of the non-living, work
against life, are destructive to it. Others are neces-
sary to life; they favor and promote the activities and
the survival of the living creature. In consequence, to
keep life in progress involves complex reactions. The
organism must avoid, retreat from, certain condi-
tions; it must seize and hold other conditions. Life
thus involves selectivity in a high degree; selectivity

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