"We perceive now that our original conception of life and the terms we use respecting it, in common parlance, are but ill-adapted to this subject when philosophically considered. We early associate life and motion so intimately that the one stands for the other. If we then investigate by anatomy, we find a curious and minute mechanism in operation, an engine and tubes for circulation, and, in short, an internal motion of every particle of the frame; and the anatomist is also led into the error of associating in his mind life with motion and organization. But when we consider the subject more closely, and divest ourselves of habits and prejudices associated with words, we perceive that, without making any vain and even dangerous attempt at definition, life is first to be contemplated as the peculiarity distinguishing one of two classes into which all matter must be arranged; the one class, which embraces all living matter, is subject to a controlling influence which resists the chemical agents, and produces a series of revolutions, in an order and at periods prescribed; the other, dead matter, is subject to lapse and change under chemical agency and the common laws of matter. "Let us examine the body of a perfect or a complicated animal. We find each organ possessed of a different power. But there is as yet no conventional language adapted to our discourse on this subject, and that is the source of many mistakes; for when a man even like Mr. Hunter had his mind illuminated upon this science, how was he to frame his language, when every word that he used had already a meaning which had no reference to the discovery he had made--to the distinct qualities which he had ascertained to belong to the living parts?... "The difference between dead and living matter will appear to be, that in the one instance the particles are permanently arranged and continue to exhibit their proper character, as we term it, until by ingenuity and practice some means are found to withdraw the arranging or uniting influence; and then the matter is chemically dissolved: resolves into its elements, and forms new combinations: whilst the life continues, not simply to arrange the particles, and to give them the order or organization of the animal body, but to whirl them in a series of revolutions, during all which the material is passive, the law being in the life. The order and succession of these changes and their duration do not result from the material of the frame, which is the same in all animals, but from that influence which we term life, and which is superadded to the material." (_Ibid._ 408.) Writing on Function Mr. Herbert Spencer discusses the following question. Its interest to our argument is unmistakable.