"I see it now, in the emotions and thoughts flickering across your face, highness. I see its effect everywhere," was the somewhat evasive response of Newton. "In Nature I perceive two categories of actions: mechanical and vegetable . By mechanical I mean, of course, just the sort of thing that Drs. Waterhouse and Leibniz discoursed of earlier: in a word, clock-work. By vegetable I do not mean turnips. That is a new and vulgar meaning of the word. I use it in its ancient sense of something animate, living, growing. It describes generative and creative processes. Clocks, even good ones, run down and wear out. The mechanical world decays. Counterpoised against this tendency to decline must be some creative principle: the active seed—the Subtile Spirit. An unimaginably tiny quantity of this, acting upon a vastly larger bulk of insipid, dead, inactive matter, wreaks immense, even miraculous transformations, to which I give the general name vegetation . Just as the general principle of Gravity manifests itself in diverse specific ways, such as tides, the orbits of comets, and the trajectories of bullets, so the vegetative principle may be perceived, by those who know how to look for it, in diverse places. Just to mention one example, which we discoursed of earlier: a flying-machine, constructed of artificial muscles, would be a mechanical device, whose fate, I believe, would be to crash to the ground, like the corpse of a bird that has died on the wing. If that machine were to take flight—which would mean sensing every fluctuation of the air, and responding in the correct way—I should ascribe that, ultimately, to the workings of some sort of vegetative principle. But Daniel is correct in thinking that it is also related to such matters as souls, miracles, and certain of the more profound and astonishing chymical transformations."