It is not improbable that there may exist, and even be discovered, higher forms and more akin to Life than those of magnetism, electricity, and constructive (or chemical) affinity appear to be, even in their finest known influences. It is not improbable that we may hereafter find ourselves justified in revoking certain of the latter, and unappropriating them to a yet unnamed triplicity; or that, being thus assisted, we may obtain a qualitative instead of a quantitative insight into vegetable animation, as distinct from animal, and that of the insect world from both. But in the present state of science, the magnetic, electric, and chemical powers are the last and highest of inorganic nature. These, therefore, we assume as presenting themselves again to us, in their next metamorphosis, as reproduction (_i.e._ growth and identity of the whole, amid the change or flux of all the parts), irritability and sensibility; reproduction corresponding to magnetism, irritability to electricity, and sensibility to constructive chemical affinity.
But before we proceed further, it behoves us to answer the objections contained in the following passage, or withdraw ourselves in time from the bitter contempt in which it would involve us. Acting under such a necessity, we need not apologise for the length of the quotation.
1. "If," says Mr. Lawrence, "the properties of living matter are to be explained in this way, why should not we adopt the same plan with physical properties, and account for gravitation, or chemical affinity, by the supposition of appropriate subtile fluids? Why does the irritability of a muscle need such an explanation, if explanation it can be called, more than the elective attraction of a salt?"
2. "To make the matter more intelligible, this vital principle is compared to magnetism, to electricity, and to galvanism; or it is roundly stated to be oxygen. 'Tis like a camel, or like a whale, or like what you please."
3. "You have only to grant that the phenomena of the sciences just alluded to depend on extremely fine and invisible fluids, superadded to the matters in which they are exhibited, and to allow further that Life, and magnetic, galvanic, and electric phenomena correspond perfectly; the existence of a subtile matter of Life will then be a very probable inference."