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.