Kant here brings forward two reasons why it is permissible to conceive of the existence of an extra-human, archetypal reason. On the one hand he admits that the existence of our own reason in its present condition is of a contingent order, and thus does not exclude the possible existence of a reason differently constituted. On the other hand, he allows that we can think of a form of reason which in every respect is the opposite of our own, without meeting any logical inconsistency.

Starting with the right-hand leaf at the bottom of Plate II, we let our eye and mind be impressed by its characteristic form, seeking to take hold of the pattern after which it is shaped. Its edge bears numerous incisions of varying depths which, however, do not disturb the roundness of the leaf as a whole. If we re-create in our imagination the 'becoming' of such a leaf, that is, its gradual growth in all directions, we receive an impression of these incisions as 'negative' forms, because, at the points where they occur, the multiplication of the cells resulting from the general growth has been retarded. We observe that this holding back follows a certain order.

In a case like this, the stem-leaves, to use Goethe's expression, 'softly steal into the calyx stage'.⁴ In the topmost leaf the plant has already achieved something which, along the other line of metamorphosis, is tackled only after the leaf plan itself has been gradually executed. In this case the calyx stage, we may say, is attained at one leap.

In the spring of 1785 he writes to a friend in a way that shows him fully aware of his new method of studying nature, which he recognized was a reading of her phenomena: 'I can't tell you how the Book of Nature is becoming readable to me. My long practice in spelling has helped me; it now suddenly works, and my quiet joy is inexpressible.' Again in the summer of the following year: 'It is a growing aware of the Form with which again and again nature plays, and, in playing, brings forth manifold life.'

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 the vertical tendency, Goethe used the term 'spiral tendency'.

Goethe has been honourably mentioned as a predecessor of Darwin. The truth is, that the idea of evolution emerging from Goethe's mode of regarding nature is the exact opposite of the one held by Darwin and - in whatever modified form - by his followers. A brief consideration of the Darwinian concepts of inheritance and adaptation will show this.

'Thus not through an extraordinary spiritual gift, not through momentary inspiration, unexpected and unique, but through consistent work did I eventually achieve such satisfactory results.' These words of Goethe - they occur in his essay, History of my Botanical Studies, which he wrote in later life as an account of his labours in this field of science - show how anxious he was that it should be rightly understood that the faculty of reading in the Book of Nature, as he knew it, was the result of a systematic training of his mind. It is important for our further studies to make clear to ourselves at this point the nature of the change which man must bring to pass within himself in order to brave Kant's 'adventure of reason'. Goethe's concept for the newly acquired faculty of cognition, exact sensorial fantasy, can give us the lead.

From these definitions emerges a conception of the properties of man's cognitional powers which agrees exactly with those on which, as we have seen, Hume built up his whole philosophy. Both allow to the reason a knowledge-material consisting only of pictures - that is, of pictures evoked in consciousness through sense-perception, and received by it from the outer world in the form of disconnected units, whilst denying it all powers, as Hume expressed it, ever 'to perceive any real connections between distinct existences'.

We now proceed to the next leaf on the same plate and observe that, whilst the initial plan is faithfully maintained, the ratio between the positive and negative forms has changed. A number of incisions, hardly yet indicated in the first leaf, have become quite conspicuous. The leaf begins to look as if it were breaking up into a number of subdivisions.

Whatever type of metamorphosis is followed by a plant (and there are others as well, so that we may even speak of metamorphoses between different types of metamorphosis!) they all obey the same basic rule, namely, that before proceeding to the next higher stage of the cycle, the plant sacrifices something already achieved in a preceding one. Behind the inconspicuous sheath of the calyx we see the plant preparing itself for a new creation of an entirely different order. As successor to the leaf, the flower appears to us time and again as a miracle. Nothing in the lower realm of the plant predicts the form, colour, scent and all the other properties of the new organ produced at this stage. The completed leaf, preceding the plant's withdrawal into the calyx, represents a triumph of structure over matter. Now, in the flower, matter is overcome to a still higher degree. It is as if the material substance here becomes transparent, so that what is immaterial in the plant may shine through its outer surface.