Goethe's thinking was mobile. It followed the whole growth process of the plant and followed how one plant form is a modification of the other. Goethe's thinking was not rigid with inflexible contours; it was a thinking in which the concepts continually metamorphose. Thereby his concepts became, if I may put it this way, intimately adapted to the process that plant nature itself goes through.

Lecture from August 30, 1921, trans. Craig Holdrege