Indeed it may be said that Donatello continued through life to affect the genius of Michelangelo by a kind of sympathy, although the elder master's naivete was soon discarded by the younger.
The second period culminated in the Cartoon for the Battle of Pisa.
This design appears to have fixed the style now known to us as Michelangelesque, and the loss of it is therefore irreparable.

It exercised the consummate science which he had acquired, his complete mastery over the male nude.

It defined his firm resolve to treat linear design from the point of view of sculpture rather than of painting proper.

It settled his determination to work exclusively through and by the human figure, rejecting all subordinate elements of decoration.

Had we possessed this epoch-making masterpiece, we should probably have known Michelangelo's genius in its flower-period of early ripeness, when anatomical learning was still combined with a sustained dependence upon Nature.