57.  It is now (I believe I may use the strong word) “ascertained” that heat and motion are fixed in quantity, and measurable in the portions that we deal with.  We can measure portions of power, as we can measure portions of space; while yet, as far as we know, space may be infinite, and force infinite.  There may be heat as much greater than the sun’s, as the sun’s heat is greater than a candle’s:  and force as much greater than the force by which the world swings, as that is greater than the force by which a cobweb trembles.  Now, on hear and force, life is inseparably dependent; and I believe, also, on a form of substance, which the philosophers call “protoplasm.”  I wish they would use English instead of Greek words.  When I want to know why a leaf is green, they tell me it is colored by “chlorophyll,” which at first sounds very instructive; but if they would only say plainly that a leaf is colored green by a thing which is called “green leaf,” we should see more precisely how far we had got.  However, it is a curious fact that life is connected with a cellular structure called protoplasm, or in English, “first stuck together;” whence, conceivably through deuteroplasms, or second stickings, and tritoplasms, or third stickings,* we reach the highest plastic phase in the human pottery, which differs from common chinaware, primarily, by a measurable degree of heat, developed in breathing, which it borrows from the rest of the universe while it lives, and which it as certainly returns to the rest of the universe, when it dies.

58.  Again, with this heat certain assimilative powers are connected, which the tendency of recent discovery is to simplify more and more into modes of one force; or finally into mere motion, communicable in various states, but not destructible.  We will assume that science has done its utmost; and that every chemical or animal force is demonstrably resolvable into heat or motion, reciprocally changing into each other.  I would myself like better, in order of thought, to consider motion as a mode of heat than heat as a mode of motion; still, granting that we have got thus far, we have yet to ask, What is heat? or what is motion?  What is this “primo mobile,” this transitional power, in which all things live, and move, and have their being?  It is by definition something different from matter, and we may call it as we choose, “first cause,” or “first light,” or “first heat;” but we can show no scientific proof of its not being personal, and coinciding with the ordinary conception of a supporting spirit in all things.

59.  Still, it is not advisable to apply the word “spirit” or “breathing” to it, while it is only enforcing chemical affinities; but, when the chemical affinities are brought under the influence of the air, and of the sun’s heat, the formative force enters and entirely different phase.  It does not now merely crystallize indefinite masses, but it gives to limited portions of matter the power of gathering, selectively, other elements proper to them, and binding those elements into their own peculiar and adopted form.