ery flash that shimmers about the horizon on a
summer's evening is determined by ascertainable conditions, and that
its direction and brightness might, if our knowledge of these were great
enough, have been calculated.

The solvency of great mercantile companies rests on the validity of the
laws which have been ascertained to govern the seeming irregularity
of that human life which the moralist bewails as the most uncertain of
things; plague, pestilence, and famine are admitted, by all but fools,
to be the natural result of causes for the most part fully within
human control, and not the unavoidable tortures inflicted by wrathful
Omnipotence upon His helpless handiwork.

Harmonious order governing eternally continuous progress--the web and
woof of matter and force interweaving by slow degrees, without a broken
thread, that veil which lies between us and the Infinite--that universe
which alone we know or can know; such is the picture which science draws
of the world, and in proportion as any part of that picture is in unison
with the rest, so may we feel sure that it is rightly painted. Shall
Biology alone remain out of harmony with her sister sciences?

Such arguments against the hypothesis of the direct creation of species
as these are plainly enough deducible from general considerations; but
there are, in addition, phenomena exhibited by species themselves, and
yet not so much a part of their very essence as to have required earlier
mention, which are in the highest degree perplexing, if we adopt the
popularly accepted hypothesis. Such are the facts of distribution in
space and in time; the singular phenomena brought to light by the study
of development; the structural relations of species upon which
our systems of classification are founded; the great doctrines of
philosophical anatomy, such as that of homology, or of the community
of structural plan exhibited by large groups of species differing very
widely in their habits and functions.

The species of animals which inhabit the sea on opposite sides of the
isthmus of Panama are wholly distinct [4] the animals and plants which
inhabit islands are commonly distinct from those of the neighbouring
mainlands, and yet have a similarity of aspect.

The mammals of the latest tertiary epoch in the Old and New Worlds
belong to the same genera, or family groups, as those which now inhabit
the same great geographical area. The crocodilian reptiles which existed
in the ear