And this is still a mystery to us. What light is we do not know—we can only speak of our own sensation of it. Nor do we know what vibrates to produce light. Hypothetical terms, such as "ether," "luminiferous-medium," and so forth, only conceal our ignorance.
Compare Job xxxviii. 10, 11, and Psa. civ. 9.
See this well summarized in Nicholson's "Manual of Zoology" (sixth edition, 1880), p. 13, et seq.
I think this is quite sufficient, without relying on the evidence of the great quantities of carbon in the earliest (Laurentian, Huronian, &c.) strata in the form of graphite. It is possible, or even probable, that this may be due to carbon supplied by masses of little specialized Thallophyte and Anophyte vegetation.