nces would
probably have been other than nitrogen, and the chemistry of living
bodies would then have been radically different from what it is. The
result would have been living forms without any analogy to those we
know, whose anatomy would have been different, whose physiology also
would have been different. Alone, the sensori-motor function would have
been preserved, if not in its mechanism, at least in its effects. It is
therefore probable that life goes on in other planets, in other solar
systems also, under forms of which we have no idea, in physical
conditions to which it seems to us, from the point of view of our
physiology, to be absolutely opposed. If its essential aim is to catch
up usable energy in order to expend it in explosive actions, it probably
chooses, in each solar system and on each planet, as it does on the
earth, the fittest means to get this result in the circumstances with
which it is confronted. That is at least what reasoning by analogy leads
to, and we use analogy the wrong way when we declare life to be
impossible wherever the circumstances with which it is confronted are
other than those on the earth. The truth is that life is possible
wherever energy descends the incline indicated by Carnot's law and where
a cause of inverse direction can retard the descent--that is to say,
probably, in all the worlds suspended from all the stars. We go further:
it is not even necessary that life should be concentrated and determined
in organisms properly so called, that is, in definite bodies presenting
to the flow of energy ready-made though elastic canals. It can be
conceived (although it can hardly be imagined) that energy might be
saved up, and then expended on varying lines running across a matter not
yet solidified. Every essential of life would still be there, since
there would still be slow accumulation of energy and sudden release.
There would hardly be more difference between this vitality, vague and
formless, and the definite vitality we know, than there is, in our
psychical life, between the state of dream and the state of waking. Such
may have been the condition of life in our nebula before the
condensation of matter was complete, if it be true that life springs
forward at the very moment when, as the effect of an inverse movement,
the nebular matter appears.

It is therefore conceivable that life might have assumed a totally
different outward appearance and designed forms very different from