forced upon man by the failure of science to discover any other
beginning for it. It cannot be said that even to-day anything
definite has been actually discovered to refute this view. All we
can say about it is that it does not run in with the general views
of modern science as to the beginning of things, and that those
who refuse to accept it must hold that, under certain conditions
which prevail, life begins by a very gradual process, similar to
that by which forms suggesting growth seem to originate even under
conditions so unfavorable as those existing in a bottle of acid.

But it is not at all necessary for our purpose to decide this
question. If life existed through a creative act, it is absurd to
suppose that that act was confined to one of the countless
millions of worlds scattered through space. If it began at a
certain stage of evolution by a natural process, the question will
arise, what conditions are favorable to the commencement of this
process? Here we are quite justified in reasoning from what,
granting this process, has taken place upon our globe during its
past history. One of the most elementary principles accepted by
the human mind is that like causes produce like effects. The
special conditions under which we find life to develop around us
may be comprehensively summed up as the existence of water in the
liquid form, and the presence of nitrogen, free perhaps in the
first place, but accompanied by substances with which it may form
combinations. Oxygen, hydrogen, and nitrogen are, then, the
fundamental requirements. The addition of calcium or other forms
of matter necessary to the existence of a solid world goes without
saying. The question now is whether these necessary conditions
exist in other parts of the universe.