of using nothing for the explanation of the plant but what one could
read from the plant itself, one must not ascribe to it any sexual
process. He was convinced that for a Goethean kind of biology it must
be possible to find, even for the process of pollination, an idea
derived from nothing but the two principles of plant life: growth and
formation.

Goethe immediately recognized the Tightness of this thought, and set
about the task of relating the pollination process to the picture of
the plant which his investigations had already yielded. His way of
reporting the result shows how fully conscious he was of its
revolutionary nature. Nor was he in any doubt as to the kind of
reception it would be given by official biology.

In observing the growth of the plant, Goethe had perceived that this
proceeds simultaneously according to two different principles. On the
one hand the plant grows in an axial direction and thereby produces its
main and side stems. To this growth principle Goethe gave the name
'vertical tendency'. Were the plant to follow this principle only, its
lateral shoots would all stand vertically one above the other. But
observation shows that the different plant species obey very different
laws in this respect, as may be seen if one links up all the leaf buds
along any plant stem; they form a line which winds spiral fashion
around it. Each plant family is distinguishable by its own
characteristic spiral, which can be represented either geometrically by
a diagram, or arithmetically by a fraction. If, for example, the leaves
are so arranged in a plant that every fifth leaf recurs on the same
side of the stem, while the spiral connecting the five successive
leaf-buds winds twice round the stem, this is expressed in botany by
the fraction 2 / 5. To distinguish this principle of plant growth from