How the two stages take form depends, not only upon the nature of heat, but essentially also upon the nature of the lead. A different substance, if caused to pass through the same media, would manifest quite different conditions. Organisms likewise are subject to being influenced by the surrounding media; they likewise take on, under the influence of these, various states of existence, and this occurs, indeed, in accordance with their nature, with that essential being which makes them organisms. This essential being is found in Goethe's ideas. Only one who is equipped with an understanding of this entity will be in a position to understand why organisms respond (react) to specific influences in a certain way and in no other. Only such a person will be in a position to form the right conceptions concerning the changeableness of the forms in which the organism appears and the laws of adaptation and the struggle for existence connected with these.

The idea of the archetypal plant took on a constantly clearer and more definite form in Goethe's mind. In the botanical garden in Padua, where he moved about in the midst of a vegetation strange to him, “the thought became more and more alive that it might be possible to develop all plant forms from a single one.” On November 17, 1786, he wrote to Knebel: “Thus, after all, my little bit of botany gives me real joy for the first time in this land, where a happier, less discontinuous vegetation is at home. I have already made quite nice observations tending toward generalizations, which will be agreeable to you also later on.” On February 19, 1787, he wrote in Rome that he was on the way toward “the discovery of new and beautiful relations showing how nature achieves something tremendous that looks like nothing, evolving the manifold out of the simple.” On March 25 he requested that Herder be informed that he would soon be ready with the archetypal plant. On April 17 he wrote down in Palermo regarding the archetypal plant the words: “Surely there must be such a thing; how else could I recognize that this or that form is a plant if all were not formed according to a model?” He had in mind the complex of formative principles which organizes the plant, which makes it what it is, by reason of which we arrive at the idea in regard to a natural object: “This is a plant.” That is the archetypal plant. As such, it is something ideal, to be held fast only in the mind, but it acquires form, it acquires a certain shape, size, color, number of organs, etc. This external form is not fixed, but can undergo endless variations, all of which are in keeping with that complex of formative principles, are derived of necessity from it. If one has grasped these formative principles, that primal image of the plant, one has laid firm hold in idea of that which nature, as it were, lays at the foundation of every single plant-individual, that out of which she calls it forth and causes it to come into existence as a result of this complex of formative laws. Indeed, we can ourselves invent plant forms in accordance with this law, which could follow of necessity and exist through the nature of the plant if the prerequisite conditions should come about.

Goethe thus endeavors, as it were, to reproduce in the mind what nature does in the formation of her entities. He wrote to Herder on May 17, 1787: “Moreover, I must tell you confidentially that I am very close to the secret of the creation of plants, and that it is the simplest thing one could imagine. The archetypal plant will be the strangest creature in the world, which nature herself ought to envy me. With this model and the key to it, one can invent plants endlessly which must be consistent—that is, if they did not exist, yet they could exist, and not some artistic or poetic shadows and appearances but possessing inner truth and inevitability. The same law can be applied to everything living.”

Here becomes apparent a still further difference between Goethe's conception and that of Darwin—that is, especially when one considers how the latter is generally applied. Darwin's view assumes that external influences, like mechanical causes, work upon the nature of an organism and modify it accordingly. To Goethe, the single alterations are various expressions of the archetypal organism (Urorganismus), which possesses within itself the capacity to take on manifold forms, and which at a particular time takes on that form which is best suited to the conditions of the external environing world. These external conditions are merely the occasion for the inner formative forces to come to manifestation in a special way. These latter alone are the constitutive principle, the creative element, in the plant. For this reason Goethe called this entity on September 6, 1787, also a hen kai pan, a one and all of the plant world.

When, now, we consider this archetypal plant itself, the following is to be said about it. The living entity is a whole enclosed within itself, which produces its state of existence through its own nature. Both in the juxtaposition of the members and in the chronological succession of the states of existence of a living entity, there is a reciprocal relationship which does not come to manifestation through a determinative influence of the sensible characteristics of the members, through the mechanical-casual determination of the later by the earlier, but is controlled by a higher Principle, belonging above the members and the states of existence. It is inherent in the nature of the whole that a definite state is fixed as the first and another as the last; and the succession of the intervening states is also determined within the idea of the whole. The preceding is dependent upon the succeeding and vice-versa. In short, in the living organism the evolution of one out of the other, the transition of states one into another, is no ready-made, finished existence of the single entity, but a constant becoming. In the plant this determination of each single organ by the whole comes to manifestation to the extent that all organs are built upon the same fundamental model. On May 17, 1787, Goethe wrote this thought to Herder in the words: “It had occurred to me that in the organ of the plant which we ordinarily designate as leaf, the true Proteus lay hidden, who can conceal and reveal himself in all forms. Forward and backward, the plant is always only leaf, so inseparably united with the future germ that we cannot imagine one without the other.”

Whereas in the animal that higher Principle which rules over every detail appears concretely before us as that which moves the organs, uses them according to its needs, etc., the plant is without such a real life Principle. In its case this reveals itself in the less definite way in that all the organs are constructed according to the same formative type—indeed, that in every part the entire plant is potentially present, and under favorable circumstances could be brought forth out of it.