but rather as one vast homogeneous fluid, and even _that_ he suggests not as a historical fact, but as the appropriate symbol of a great fundamental truth. The first effort of magnetic power, the first step from indifference to difference, from formless homogeneity to independent existence, is seen in the tranquil deposition of crystals; and an increasing tendency to difference is observable in the increasing multitude of strata, till we come to organic life; of which the vegetable and animal worlds may be regarded as opposite poles; carbon prevailing in the former and azote in the latter; and vegetation being characterised by the predominance of magnetism in its highest power, as reproduction; whilst the animal tribes evince the power of electricity, as shown in irritability and sensibility. Passing over the forms of vegetation, we come to the polypi, corallines, &c., in which individuality appears in its first dawn; for a multitude of animals form, as it were, a common animal, and different genera pass into each other, almost indistinguishably. The tubipora of the corals connects with the serpula of the conchylia. In the _mollusca_ the separation of organs becomes more observable; in the higher species there are rudiments of nerves, and an exponent, though scarcely distinguishable, of sensibility. In the snail, and muscle, the separation of the fluid from the solid is more marked, yet the prevalence of the carbonic principle connects these and the preceding classes, in a certain degree, with the vegetable creation. “But the _insect_ world, taken at large (says Mr. Coleridge) appears as an intense _Life_, that has struggled itself loose, and become emancipated from vegetation—_Floræ liberti, et libertini_!” In insects we first find the distinct commencement of a separation between the muscular system, that is, organs of irritability, and the nervous system, that is, organs of sensibility; the former, however, maintaining a pre-eminence throughout, and the nerves themselves being probably subservient to the motory power. With the fishes begins an internal system of bones, but these are the results of a comparatively imperfect formation, being in general little more than mere gristle. In birds we find a sort of synthesis of the powers of fish and insects. In all three, the powers are under the predominance of irritability; but sensibility, which is dormant in the insect, begins to awaken in the fish, and, though still subordinate, is quite awake in the bird, of which no better proof can be given than its power of sound, with the rudiments of modulation, in the large class of singing birds, and in some others a tendency to acquire and to imitate articulate speech. The next step of ascent brings us to the _mammalia_; and in these, including beasts and men, the complete and universal presence of a nervous system raises sensibility to its due place and rank among the animal powers.