Finally, of individuals, the living power will be most intense in that individual which, as a whole, has the greatest number of integral parts presupposed in it; when, moreover, these integral parts, together with a proportional increase of their interdependence, as _parts_, have themselves most the character of wholes in the sphere occupied by them. A mathematical point, line, or surface, is an _ens rationis_, for it expresses an intellectual act; but a physical atom is _ens fictitium_, which may be made subservient, as ciphers are in arithmetic, to the purposes of hypothetical construction, _per regulam falsi_; but transferred to _Nature_, it is in the strictest sense an _absurd_ quantity; for extension, and consequently divisibility, or _multeity_,(11) (for space cannot be divided,) is the indispensable condition, under which alone anything can _appear_ to us, or even be _thought_ of, as a _thing_. But if it should be replied, that the elementary particles are atoms not positively, but by such a hardness communicated to them as is relatively invincible, I should remind the assertor that _temeraria citatio supernaturalium est pulvinar intellectús pigri_, and that he who requires me to believe a miracle of his own dreaming, must first work a miracle to convince me that he had dreamt by inspiration. Add, too, the gross inconsistency of resorting to an immaterial influence in order to complete a system of materialism, by the exclusion of all modes of existence which the theorist cannot in imagination, at least, _finger_ and _peep_ at! Each of the preceding gradations, as above defined, might be represented as they exist, and are realised in Nature. But each would require a work for itself, co-extensive with the science of metals, and that of fossils (both as geologically applied); of crystallization; and of vegetable and animal physiology, in all its distinct branches. The nature of the present essay scarcely permits the space sufficient to illustrate our meaning. The proof of its probability (for to that only can we arrive by so partial an application of the hypothesis), is to be found in its powers of solving the particular class of phenomena, that form the subjects of the present inquisition, more satisfactorily and profitably than has been done, or even attempted before.