is probable that already at that time he overestimated the value of this knowledge for the artist. Following the guide-rope of the painter's need, he was then driven further and further to investigate the objects of the art of painting, such as animals and plants, and the proportions of the human body, and to follow the path from their exterior to their interior structure and biological functions, which really also express themselves in their appearance and should be depicted in art. And finally he was pulled along by this overwhelming desire until the connection was torn from the demands of his art, so that he discovered the general laws of mechanics and divined the history of the stratification and fossilization of the Arno-valley, until he could enter in his book with capital letters the cognition: Il sole non si move (The sun does not move). His investigations were thus extended over almost all realms of natural science, in every one of which he was a discoverer or at least a prophet or forerunner.[1] However, his curiosity continued to be directed to the outer world, some-
- ↑ For an enumeration of his scientific attainments see Marie
