Naturally, should science class life as the highest or most complex of the modes of material motion, the question would arise concerning the manner in which this conversion were made possible. The answer must be that the ultimate particles of the matter composing the living thing are so arranged or organized that the great natural forces may be converted into life force. It is possible by passing heat through certain substances to make them luminous, thus converting heat into light; by employing a dynamo, mechanical energy may be converted into electrical energy; by coiling a wire around a rod of soft iron, electricity may be converted into magnetism. In short, it is well understood in science, that by the use of the right machines one form of energy may be changed into another. It is generally assumed, that the human body is so organized that the forces of heat, light and undoubtedly others, may be converted into higher forms, peculiar to living things.[A]
[Footnote A: Compare, Fiske, Outlines of Cosmic Philiosophy, chap. XVI. Pearson, Grammar of Science, pp. 404-407. Dolbear, Matter, Ether and Motion, chap. XI, pp. 294-297.]
[Sidenote: Protoplasm, a highly organized body, is always associated with life.]
To substantiate this view, it may be recalled that the fundamental chemical individual in living thing is a very complex, unstable substance known as protoplasm. No living cell exists without the presence of this substance. It is far from being known well, as yet, but enough is known to enable science to say that it is composed of several elements, so grouped and regrouped as to transcend all present methods of research.[A] By means of this highly organized body, it is assumed that the ordinary forces of nature are worked over and made suited for the needs of the phenomena of life.
[Footnote A: Pearson, Grammar of Science, p. 408.]
The existence of the complex life-characteristic substance protoplasm, renders probable the view that living things, after all, differ from the rest of creation only in the kind and degree of their organization, and that life, as the word is ordinarily used, depends upon a certain kind or organization of matter,[A] which leads to a certain kind of motion.
[Footnote A: Tyndall, Fragments of Science. II, chaps. IV and VI.]
As to the origin of the special organization called life, science has nothing to say. Science is helpless when she deals with the beginning of things. The best scientific explanation of life is that it is a very complex mode of motion occasioned by a highly complex organization of the matter and ether of the living body.
There are still some students who prefer to believe in the existence of a special vital force, which is not subject to the laws that govern other forces. This view, however, is so inconsistent with the modern understanding of the contents of the universe that it has few followers.
[Sidenote: The modern conception of life is very recent.]