Goethe's observation of the single plant in statu agendi had trained
him to recognize things of quite different outer appearance as
identical in their inner nature. Leaf, sepal, petal, etc., much as they
differ outwardly, yet showed themselves to him as manifestations of one
and the same spiritual archetype. His idea of Metamorphosis enabled him
to reduce what in outer appearance seems incompatibly different to its
common formative principle. His next step was to observe the different
appearances of one and the same species in different regions of the
earth, and thus to watch the capacity of the species to respond in a
completely flexible way to the various climatic conditions, yet without
concealing its inner identity in the varying outer forms. His travels
in Switzerland and Italy gave him opportunity for such observations,
and in the Alpine regions especially he was delighted at the variations
in the species which he already knew so well from his home in Weimar.
He saw their proportions, the distances between the single parts, the
degree of lignification, the intensity of colour, etc., varying with
the varied conditions, yet never concealing the identity of the
species.

Having once advanced in his investigations from metamorphosis in the
parts of the single plant to metamorphosis among different
representatives of single plant species, Goethe had to take only one
further, entirely decisive, step in order to recognize how every member
of the plant kingdom is the manifestation of a single formative
principle common to them all. He was thus faced with the momentous task
of preparing his spirit to think an idea from which the plant world in
its entire variety could be derived.

Goethe did not take such a step easily, for it was one of his
scientific principles never to think out an idea prematurely. He was