for--which constitutes so vast and plain a practical distinction
between living bodies and those which do not live, is an ultimate
fact; indicating as such, the existence of a broad line of
demarcation between the subject matter of biological and of all
other science."

In another passage he wrote:

"Looking back through the prodigious vista of the past I find no
record of the commencement of life, and therefore I am devoid of
any means of forming a definite conclusion as to the conditions
of its appearance. Belief, in the scientific sense of the word,
is a serious matter, and needs strong foundations. To say,
therefore, in the admitted absence of evidence, that I have any
belief as to the mode in which the existing forms of life have
originated, would be using words in a wrong sense. But
expectation is permissible where belief is not; and if it were
given me to look beyond the abyss of geologically recorded time
to the still more remote period when the earth was passing
through physical and chemical conditions which it can no more see
again than a man can recall his infancy, I should expect to be a
witness of the evolution of living protoplasm from non-living
matter. I should expect to see it appear under forms of great
simplicity, endowed, like existing fungi, with the power of
determining the formation of new protoplasm from such matters as
ammonium carbonates, oxalates, and tartrates, alkaline and earthy
phosphates, and water, without the aid of light. That is the
expectation to which analogical reasoning leads me, but I beg you
once more to recollect that I have no right to call my opinion
anything but an act of philosophical faith."

Since these words were written the reasons for Huxley's "philosophic
faith" have been strengthened by later discoveries, and perhaps a
majority of biologists would take the view that except for practical
purposes there is no sound reason for placing living and inorganic
aggregations of matter in totally different categories. But even if
the main outline of the theory of evolution were proved beyond the
possibility of doubt, if we could trace existing plants and animals
backwards with the accuracy of a genealogist and find that they had
been developed, under purely physical "laws" from a few simple forms,
and if we could understand exactly how these