ology; and I hold that our present knowledge
of these facts is sufficiently thorough and extensive to justify the
assertion that all future philosophical and theological speculations
will have to accommodate themselves to some such common body of
established truths as the following:--

1. Plants and animals have existed on our planet for many hundred
thousand, probably millions, of years. During this time, their forms,
or species, have undergone a succession of changes, which eventually
gave rise to the species which constitute the present living
population of the earth. There is no evidence, nor any reason to
suspect, that this secular process of evolution is other than a part
of the ordinary course of nature; there is no more ground for
imagining the occurrence of supernatural intervention, at any moment
in the development of species in the past, than there is for supposing
such intervention to take place, at any moment in the development of
an individual animal or plant, at the present day.

2. At present, every individual animal or plant commences its
existence as an organism of extremely simple anatomical structure; and
it acquires all the complexity it ultimately possesses by gradual
differentiation into parts of various structure and function. When a
series of specific forms of the same type, extending over a long
period of past time, is examined, the relation between the earlier and
the later forms is analogous to that between earlier and later stages
of individual development. Therefore, it is a probable conclusion
that, if we could follow living beings back to their earlier states,
we should find them to present forms similar to those of the
individual germ, or, what comes to the same thing, of those lowest
known organisms which stand upon the boundary line between plants and
animals. At present, our knowledge of the ancient living world stops
very far short of this point.

3. It is generally agreed, and there is certainly no evidence to the
contrary, that all plants are devoid of consciousness; that they
neither feel, desire, nor think. It is conceivable that the evolution
of the primordial living substance should have taken place only along
the plant line. In that case, the result might have been a wealth of
vegetable life, as great, perhaps as varied, as at present, though
certainly widely different from the present flora, in the evolution of
which animals have played so great a part. But the living worl