I dare say I may have to return to this point by-and-by; but having
dealt thus far with our logical methods, I must now turn to something
which, perhaps, you may consider more interesting, or, at any rate,
more tangible. But in reality there are but few things that can be
more important for you to understand than the mental processes and the
means by which we obtain scientific conclusions and theories.1 Having
granted that the inquiry is a proper one, and having determined on the
nature of the methods we are to pursue and which only can lead to
success, I must now turn to the consideration of our knowledge of the
nature of the processes which have resulted in the present condition of
organic nature.

Here, let me say at once, lest some of you misunderstand me, that I have
extremely little to report. The question of how the present condition
of organic nature came about, resolves itself into two questions. The
first is: How has organic or living matter commenced its existence? And
the second is: How has it been perpetuated? On the second question I
shall have more to say hereafter. But on the first one, what I now
have to say will be for the most part of a negative character.

If you consider what kind of evidence we can have upon this matter, it
will resolve itself into two kinds. We may have historical evidence
and we may have experimental evidence. It is, for example,
conceivable, that inasmuch as the hardened mud which forms a
considerable portion of the thickness of the earth's crust contains
faithful records of the past forms of life, and inasmuch as these
differ more and more as we go further down,--it is possible and
conceivable that we might come to some particular bed or stratum which
should contain the remains of those creatures with which organic life