This marvellous and divinely inspired Leonardo...would have been proficient at his early lessons if he had not been so volatile and unstable; for he was always setting himself to learn many things only to abandon them almost immediately....
Clearly, it was because of his profound knowledge of painting that Leonardo started so many things without finishing them; for he was convinced that his hands, for all their skill, could never perfectly express the subtle and wonderful ideas of his imagination....
-Giorgio Vasari on Leonardo da Vinci...