[Footnote 6: _Darwin and Copernicus_. This is the title of an address delivered by Du Bois-Reymond on 25th January 1883, in the Berlin Academy of Sciences, and afterwards published in his _Collected Addresses_ (_vol_. ii. 1887). As the author himself mentions in a note (p. 500) that this gave rise, "most unmeritedly," to great excitement, and called down upon him the violent attacks of the clerical press, I may be allowed to point out here that it contained nothing new, I myself, fifteen years previously, in my lectures on "The Origin and Genealogy of the Human Race," having carried out in detail the comparison between Darwin and Copernicus, and the service rendered by these two heroes in putting an end to the anthropocentric and geocentric views of the world. (See the Third Series in Virchow and Holtzendorff's _Collection of Popular Scientific Lectures_, Nos. 53 and 54, 1868, 4th ed., 1881.) When Du Bois-Reymond says, "For me, Darwin is the Copernicus of the organic world," I am the more pleased to find that he agrees (partly in identical words) with my way of thinking, as he himself, quite unnecessarily, takes up an attitude of opposition towards me. The same is the case with regard to the explanation of innate ideas by Darwinism, which he has attempted in his address (1870) on "Leibnitzian Ideas in Modern Science" (vol. i. of the _Collected Addresses_). Here also he is most agreeably at one with me in what, four years before, I had elaborated in my _General Morphology_ (vol. ii. p. 446), and in my _Natural History of Creation_ (1868). "The laws of heredity and adaptation explain to us how it is that _à priori_ ideas have been developed out of what was originally _à posteriori_ knowledge," etc. I cannot fail to be highly flattered in being able in these last days to greet the renowned orator of the Berlin Academy as a friend and patron of the _Natural History of Creation_, which he had previously designated a bad romance. But his winged words are not on that account to be forgotten, that "the genealogical trees of phylogeny are about as much worth as, in the eyes of the historical critic, are those of the Homeric heroes" (_Darwin versus Galiani_, 1876).]