very basic ideas of the science of evolution. He says, for instance
(1807): "When we compare plants and animals in their most rudimentary
forms, it is almost impossible to distinguish between them. But we may
say that the plants and animals, beginning with an almost inseparable
closeness, gradually advance along two divergent lines, until the
plant at last grows in the solid, enduring tree and the animal attains
in man to the highest degree of mobility and freedom." That Goethe was
not merely speaking in a poetical, but in a literal genealogical,
sense of this close affinity of organic forms is clear from other
remarkable passages in which he treats of their variety in outward
form and unity in internal structure. He believes that every living
thing has arisen by the interaction of two opposing formative forces
or impulses. The internal or "centripetal" force, the type or "impulse
to specification," seeks to maintain the constancy of the specific
forms in the succession of generations: this is heredity. The external
or "centrifugal" force, the element of variation or "impulse to
metamorphosis," is continually modifying the species by changing their
environment: this is adaptation. In these significant conceptions
Goethe approaches very close to a recognition of the two great
mechanical factors which we now assign as the chief causes of the
formation of species.

However, in order to appreciate Goethe's views on morphology, one must
associate his decidedly monistic conception of nature with his
pantheistic philosophy. The warm and keen interest with which he
followed, in his last years, the controversies of contemporary French
scientists, and especially the struggle between Cuvier and Geoffroy
St. Hilaire (see chapter 4 of The History of Creation), is very
characteristic. It is also necessary to be familiar with his style and
general tenour of thought in order to appreciate rightly the many