In his History of my Botanical Studies Goethe mentions, besides Shakespeare and Spinoza, Linnaeus as one who had most influenced his own development. Concerning Linnaeus, however, this is to be understood in a negative sense. For when Goethe, himself searching for a way of bringing the confusing multiplicity of plant phenomena into a comprehensive system, met with the Linnaean system, he was, despite his admiration for the thoroughness and ingenuity of Linnaeus's work, repelled by his method. Thus by way of reaction, his thought was brought into its own creative movement: 'As I sought to take in his acute, ingenious analysis, his apt, appropriate, though often arbitrary laws, a cleft was set up in my inner nature: what he sought to hold forcibly apart could not but strive for union according to the inmost need of my own being.'
Linnaeus's system agonized Goethe because it demanded from him 'to memorize a ready-made terminology, to hold in readiness a certain number of nouns and adjectives, so as to be able, whenever any form was in question, to employ them in apt and skilful selection, and so to give it its characteristic designation and appropriate position.' Such a procedure appeared to Goethe as a kind of mosaic, in which one ready-made piece is set next to another in order to produce out of a thousand details the semblance of a picture; and this was 'in a certain way repugnant' to him. What Goethe awoke to when he met Linnaeus's attempt at systematizing the plant kingdom was the old problem of whether the study of nature should proceed from the parts to the whole or from the whole to the parts.
Seeing, therefore, how it became a question for Goethe, at the very beginning of his scientific studies, whether a natural classification of nature's phenomena could be achieved, we can understand why he was so overjoyed when, towards the end of his life, in a field of observation which had meanwhile caught much of his interest, he met with a classification which showed, down to the single names employed, that it had been read off from reality.
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The following is a comprehensive description of Goethe's meteorological views, which he gave a few years before his death in one of his conversations with his secretary, Eckermann:
'I compare the earth and her hygrosphere3 to a great living being perpetually inhaling and exhaling. If she inhales, she draws the hygrosphere to her, so that, coming near her surface, it is condensed to clouds and rain. This state I call water-affirmative (WasserBejahung). Should it continue for an indefinite period, the earth would be drowned. This the earth does not allow, but exhales again, and sends the watery vapours upwards, when they are dissipated through the whole space of the higher atmosphere. These become so rarefied that not only does the sun penetrate them with its brilliancy, but the eternal darkness of infinite space is seen through them as a fresh blue. This state of the atmosphere I call water-negative (WasserVerneinung). For just as, under the contrary influence, not only does water come profusely from above, but also the moisture of the earth cannot be dried and dissipated - so, on the contrary, in this state not only does no moisture come from above, but the damp of the earth itself flies upwards; so that, if this should continue for an indefinite period, the earth, even if the sun did not shine, would be in danger of drying up.' (llth April 1827.)
Goethe's notes of the results of his meteorological observations show how in them, too, he followed his principle of keeping strictly to the phenomenon. His first concern is to bring the recorded measurements of weather phenomena into their proper order of significance. To this end he compares measurements of atmospheric temperature and local density with barometric measurements. He finds that the first two, being of a more local and accidental nature, have the value of 'derived' phenomena, whereas the variations in the atmosphere revealed by the barometer are the same over wide areas and therefore point to fundamental changes in the general conditions of the earth. Measurements made regularly over long periods of time finally lead him to recognize in the barometric variations of atmospheric pressure the basic meteorological phenomenon.
In all this we find Goethe carefully guarding himself against 'explaining' these atmospheric changes by assuming some kind of purely mechanical cause, such as the accumulation of air-masses over a certain area or the like. Just as little would he permit himself lightly to assume influences of an extra-terrestrial nature, such as those of the moon. Not that he would have had anything against such things, if they had rested on genuine observation. But his own observations, as far as he was able to carry them, told him simply that the atmosphere presses with greater or lesser intensity on the earth in more or less regular rhythms. He was not abandoning the phenomenal sphere, however, when he said that these changes are results of the activity of earthly gravity, or when he concluded from this that barometric variations were caused by variations in the intensity of the field of terrestrial gravity, whereby the earth sometimes drew the atmosphere to it with a stronger, and sometimes with a weaker, pull.
He was again not departing from the realm of the phenomenal when he looked round for other indications in nature of such an alternation of drawing in and letting forth of air, and found them in the respiratory processes of animated beings. (To regard the earth as a merely physical structure was impossible for Goethe, for he could have done this only by leaving out of account the life visibly bound up with it.) Accordingly, barometric measurements became for him the sign of a breathing process carried out by the earth.
Alongside the alternating phases of contraction and expansion within the atmosphere, Goethe placed the fact that atmospheric density decreases with height. Observation of differences in cloud formation at different levels, of the boundary of snow formation, etc., led him to speak of different 'atmospheres', or of atmospheric circles or spheres, which when undisturbed are arranged concentrically round the earth. Here also he saw, in space, phases of contraction alternating with phases of expansion.