ion has done almost nothing, and hence it can
only communicate with the smallest possible area of Environment. An
insect, in virtue of its more complex structure, corresponds with a
wider area. Nature has endowed it with special faculties for reaching
out to the Environment on many sides; it has more life than the Amoeba.
In other words, it is a higher animal. Man again, whose body is still
further differentiated, or broken up into different correspondences,
finds himself _en rapport_ with his surroundings to a further extent.
And therefore he is higher still, more living still. And this law, that
the degree of Life varies with the degree of correspondence, holds to
the minutest detail throughout the entire range of living things. Life
becomes fuller and fuller, richer and richer, more and more sensitive
and responsive to an ever-widening Environment as we arise in the chain
of being.

Now it will speedily appear that a distinct relation exists, and must
exist, between complexity and longevity. Death being brought about by
the failure of an organism to adjust itself to some change in the
Environment, it follows that those organisms which are able to adjust
themselves most readily and successfully will live the longest. They
will continue time after time to effect the appropriate adjustment, and
their power of doing so will be exactly proportionate to their
complexity--that is, to the amount of Environment they can control with
their correspondences. There are, for example, in the Environment of
every animal certain things which are directly or indirectly dangerous
to Life. If its equipment of correspondences is not complete enough to
enable it to avoid these dangers in all possible circumstances, it must
sooner or later succumb. The organism then with the most perfect set of
correspondences, that is, the highest and most complex organism, has an
obvious advantage over less complex forms. It can adjust itself more
perfectly and frequently. But this is just the biological way of saying
that it can live the longest. And hence the relation between complexity
and longevity may be expressed thus--the most complex organisms are the
longest lived.

To state and illustrate the proposition conversely may the point still
further clear. The less highly organized an animal is, the less will be
its chance of remaining in lengthened correspondence with its
Environment. At some time or other in its career circumstances are sure
to oc