[46] _Le Regne Animal_, i., p. 6, 1817. [47] _Histoire des Progres des Sciences naturelles depuis 1789_, i., p. 310, 1826. [48] _Recherches sur les Ossemens Fossiles_, i., p. 60, 1812. [49] _Ossemens fossiles_, i., p. 60. [50] _Loc. cit._, i., p. 63. [51] _Lecons d'Anatomie Comparee_, i., p. 6. [52] _Le Regne Animal_, i., p. 16. [53] _Hist. Prog. Sci. Nat._, i., p. 187, 1826. [54] _Lecons_, i., p. 58. [55] _Loc. cit._, i., Article iii. [56] _Loc. cit._, i., p. 60. [57] _Regne Animal_, i., p. xx. [58] Cuvier, _Hist. Prog. Sci. Nat._, i., p. 288, 1826. [59] _Regne Animal_, i., p. 10. [60] _Regne Animal_, p. 55. [61] First propounded by Cuvier in 1812, _Ann. Mus. d'Hist. Nat._, xix. [62] _Regne Animal_, i., p. 19. [63] _Loc. cit._, p. 20. [64] _Recherches sur les Ossemens Fossiles_, i., p. 74, 1812. [65] _Loc. cit._, p. 79. [66] See C. Deperet, _Les transformations du Monde animal_, Paris, 1907, and G. Steinmann, _Die geologischen Grundlagen der Abstammungslehre_, Leipzig, 1908. [67] _Recherches_, i., p. 81. [68] _Regne Animal_, i., p. 91. [69] _Ossemens Fossiles_, i., p. 26. CHAPTER IV GOETHE Science, in so far as it rises above the mere accumulation of facts, is a product of the mind's creative activity. Scientific theories are not so much formulae extracted from experience as intuitions imposed upon experience. So it was that Goethe, who was little more than a dilettante,[70] seized upon the essential principles of a morphology some years before that morphology was accepted by the workers. Goethe is important in the history of morphological method because he was the first to bring to clear consciousness and to express in definite terms the idea on which comparative anatomy before him was based, the idea of the unity of plan. We have seen that this idea was familiar to Aristotle and that it was recognised implicitly by all who after him studied structure comparatively. In Goethe's time the idea had become ripe for expression. It was used as a guiding principle in Goethe's youth particularly by Vicq d'Azyr and by Camper. The former (1748-1794), who discovered[71] in the same year as Goethe (1784) the intermaxillary bone in man, pointed out the homology in structure between the fore limb and the hind limb, and interpreted certain rudimentary bones, the intermaxillaries and rudimentary clavicles, in the light of the theory that Vertebrates are built upon one single plan of structure. "Nature seems to operate always according to an original and general plan, from which she departs with regret and whose traces we come across everywhere" (Vicq d'Azyr, quoted by Flourens, _Mem. Acad. Sei._, XXIII., p. xxxvi.).