[18] Grote.
[19] Grote's "Plato," iii, 282.
[20] See, as to the reception of the Platonic Demiurgus by the Alexandrian Jews, first chapter.
[21] "Origin of Species," p. 428, American edition, from the sixth English. New York: D. Appleton & Co., 1882.
[22] Mr. Darwin refers to Mr. Herbert Spencer's theory of "the necessary acquirement of each mental power and capacity by gradation"; and indeed it is apparent that this class of philosophers have constructed a theory which denies the creation of the human mind as a spiritual essence, independent of matter, although some of them may adhere to the idea that it was God who caused matter to evolve out of its own action the substance or existence that we call mind.
[23] "Origin of Species," p. 69.
[24] For the illustrations of both kinds of selection I must refer the reader to Mr. Darwin's works. In regard to birds, he makes the sexual selection operate less by the "law of battle" among the males, or by fighting, and more by the attractions of plumage and voice, by which the males carry on their rivalry for the choice of the females in pairing. But he attributes the same effect to the sexual selection in birds as in the other animals, namely, the transmission to offspring, and chiefly to the male offspring, of those peculiarities of structure which have given to the male parent the victory over his competitors.
[25] A very low form of fish, without brain, vertebral column, or heart, classed by the older naturalists among the worms. ("Descent of Man," p. 159.) The technical name of the lancelet is Amphioxus.
[26] "Origin of Species," p. 146.
[27] The kangaroos and opossums are of this group.