secret of life is merely a chemical reaction.  A living body awakens a train of ideas in our minds that a non-living fails to awaken—­a train of ideas that belong to another order from that awakened by scientific demonstration.  We cannot blame science for ruling out that which it cannot touch with its analysis, or repeat with its synthesis.  The phenomena of life are as obvious to us as anything in the world; we know their signs and ways, and witness their power, yet in the alembic of our science they turn out to be only physico-chemical processes; hence that is all there is of them.  Vitality, says Huxley, has no more reality than the horology of a clock.  Yet Huxley sees three equal realities in the universe—­matter, energy, and consciousness.  But consciousness is the crown of a vital process.  Hence it would seem as if there must be something more real in vitality than Huxley is willing to admit.

II

Nearly all the later biologists or biological philosophers are as shy of the term “vital force,” and even of the word “vitality,” as they are of the words “soul,” “spirit,” “intelligence,” when discussing natural phenomena.  To experimental science such words have no meaning because the supposed realities for which they stand are quite beyond the reach of scientific analysis.  Ray Lankester, in his “Science from an Easy Chair,” following Huxley, compares vitality with aquosity, and says that to have recourse to a vital principle or force to explain a living body is no better philosophy than to appeal to a principle of aquosity to explain water.  Of course words are words, and they have such weight with us that when we have got a name for a thing it is very easy to persuade ourselves that the thing exists.  The terms “vitality,” “vital force,” have long been in use, and it is not easy to convince one’s self that they stand for no reality.  Certain it is that living and non-living matter are sharply separated, though when reduced to their chemical constituents in the laboratory they are found to be identical.  The carbon, the hydrogen, the nitrogen, the oxygen, and the lime, sulphur, iron, etc., in a living body are in no way peculiar, but are the same as these elements in the rocks and the soil.  We are all made of one stuff; a man and his dog are made of one stuff; an oak and a pine are made of one stuff; Jew and Gentile are made of one stuff.  Should we be justified, then, in saying that there is no difference between them?  There is certainly a moral and an intellectual difference between a man and his dog, if there is no chemical and mechanical difference.  And there is as certainly as wide or a wider difference between living and non-living matter, though it be beyond the reach of science to detect.  For this difference we have to have a name, and we use the words “vital,” “vitality,” which seem to me to stand for as undeniable realities as the words heat, light, chemical affinity, gravitation.