It will give a new and sure basis of classification. Indeed, this grand fact of the grouping of all organic beings seems inexplicable on any other theory. Read the interminable disputes of the naturalists as to what are species and what varieties, and you will see what a scientific chaos classification up to this day is. How the cumbersome catalogues of species increase ! Meanwhile the difficulties increase, also, instead of diminishing with the extension of their researches.

That is a great fact, too, which Mr. DARWIN so impressively teaches -- the imperfection of the geological record -- and must go largely to modify existing palaeontologic conceptions.

And what a vast background he lights up! What flowing aeons mark the ascent from the Silurian Mollusks to man -- gulfs of time over which the mind grows dizzy in the attempt to gaze, and we feel the shiver of eternity pass over us! It is well to feed the mind with this sense of the amplitude of time, as a counter-agent of our petty and contracted chronologies.

It is the leading idea of modern science that we need not go in search of any other causes than those which are at present in action, for an explanation of the phenomena of Nature. Modern geology has banished the notion of sudden cataclysms, by showing that the same agencies are now at work which have brought about all the wonders of the up-piling of the strata of the globe. We are thus introduced into the grand idea of growth -- of the enormous effect of existing agencies, when spread over a great period of time.

DARWIN puts himself abreast these same tendencies. And just as LYELL has banished from Geology the notion of sudden cataclysms, DARWIN threatens to banish from Zoology the notion of sudden creations. Together, we feel justified in saying, they have laid the foundation of one of the mightiest changes in philosophical thought. It is certainly more in accordance with our ideas of the philosophy of causation to believe that the entire hierarchy of animate organisms are the result of the continuity of one mode of operation throughout the whole period that has elapsed since life was first introduced into our planet. It harmonizes better with our highest ideas of divine foresight, to believe that the scheme of evolution was originally made so perfect as to require no subsequent interference. We have no sympathy with those who, to use the admirable language of BADEN POWELL -- "behold the Deity more clearly in the dark than in the light -- in confusion, interruption and catastrophe, more than in order, continuity and progress."

V.

The most important contribution to modern thought is undoubtedly the indirect teachings of physical science. For, magnificent though the direct teachings be, the indirect are perhaps still more wonderful: the former have relation but to the material world, while the latter influence the whole of man's speculative activity. Indeed the only part of science that can ever profoundly touch the great laity are its glorious indirections -- its grand out-croppings of truth. In this regard there is much for science yet to attain: science needs literature just as much as literature needs science. He is the master of science who makes his facts but initial, leading to heights where new vistas open in flashes of beauty and repose. It is a significant fact that certain propositions recommend themselves and find acceptance even though not fortified by authority. They seem to find metaphysical support and interior warranties. Who can fail to see that such doctrines as the Nebular hypothesis, the doctrine of Development, &c., aside altogether from their scientific validity, have an indirect import to the culture, far more potent than all their direct bearings?

It would seem as if the doctrine of "attractions proportioned to destinies" held equally true in science as in sociology. HARVEY's discovery of the circulation of the blood is recorded to have found acceptance from no physician over forty years old. Perhaps DARWIN felt that to his own theory some such elective affinities might apply. "I look," says he, towards the close of the volume, "with confidence to the future, to young and rising naturalists, who will be able to view both sides of the question with impartiality."

In that future, to which he looks forward, he will not, we apprehend, be regarded as having drawn the cosmic circle of life, but rather as having indicated one of its arcs. At all events, it seems to be a historic law that the greater portion of truths in the theory of nature first appear as purple mirages --ruddy and auroral streaks gilding the matin of man's mind ; but the appointed time- duly brings up the perfect thought, fraught with the wealth of invisible climee, and Hooding the age with the sunlight of science.