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.