two
main factors in all Evolution--the nature of the organism and the nature
of the conditions. We have chosen our illustration from the highest or
human species in order to define the meaning of these factors in the
clearest way; but it must be remembered that the development of man
under these directive influences is essentially the same as that of any
other organism in the hands of Nature. We are dealing therefore with
universal Law. It will still further serve to complete the conception of
the general principle if we now substitute for the casual phrases by
which the factors have been described the more accurate terminology of
Science. Thus what Biography describes as parental influences, Biology
would speak of as Heredity; and all that is involved in the second
factor--the action of external circumstances and surroundings--the
naturalist would include under the single term Environment. These two,
Heredity and Environment, are the master-influences of the organic
world. These have made all of us what we are. These forces are still
ceaselessly playing upon all our lives. And he who truly understands
these influences; he who has decided how much to allow to each; he who
can regulate new forces as they arise, or adjust them to the old, so
directing them as at one moment to make them cooeperate, at another to
counteract one another, understands the rationale of personal
development. To seize continuously the opportunity of more and more
perfect adjustment to better and higher conditions, to balance some
inward evil with some purer influence acting from without, in a word to
make our Environment at the same time that it is making us--these are
the secrets of a well-ordered and successful life.

In the spiritual world, also, the subtle influences which form and
transform the soul are Heredity and Environment. And here especially
where all is invisible, where much that we feel to be real is yet so
ill-defined, it becomes of vital practical moment to clarify the
atmosphere as far as possible with conceptions borrowed from the natural
life. Few things are less understood than the conditions of the
spiritual life. The distressing incompetence of which most of us are
conscious in trying to work out our spiritual experience is due perhaps
less to the diseased will which we commonly blame for it than to
imperfect knowledge of the right conditions. It does not occur to us how
natural the spiritual is. We still strive for some st