of things; they are objective, concrete, final, exact: they are so because they are thought-determined (not mere sense-conditioned) relations. The distinction between the philosophy of nature and natural science is one not merely of quantity ("generalty"), but of quality. In nature as object of science externality of parts rules: each thing is outside all others, is an individual by itself, its relation to others being mechanical: even as “cause” of some other thing, a thing is wholly outside of that other. For philosophy, nature is everywhere fraught with the tendency towards inward identity, the unity of thought; cause and effect are two organically related forms of the same self-distinguishing reality; a genus is not merely a collective unity, either of attributes or of individual things, but an underlying combining activity, a living, synthetic energy.
To exhibit the difference of method and spirit between the philosophy of nature and natural science by means of examples, let us consider the doctrines, say, of the conservation of energy, instead of being merely “given” as a general “fact” or, rather, perhaps, as a postulate, is a self-evident, identical proposition, since energy, and energy alone, is being in activity, energy. For natural science, it is “given,” is not really demonstrable by any means within its cognizance which does not presuppose the truth of the “law,” all so-called demonstrations of it being mere tautologies or restatements of the fact itself as presupposed in every individual experiment and observation used to “prove” the law. Strictly speaking, indeed, natural science as based on (limited) observation and experiment, does not of itself prove any (universal) law or truth; hence, of course, not that of the conservation of energy. Still more “given” (undemonstrable), if that were possible, for natural science is the distinction of energy as kinetic (real) and potential (ideal): and indeed the tendency is manifested among physical speculatists to regard all energy as kinetic, which, however, cannot really be done without doing violence to (observed) “fact,” to consistency in physical theory as such, and to philosophical principles of nature.
