CORNELIUS CELSUS.
The highest good is wisdom, the chief evil is suffering in the body. Because, as we are composed of two things, that is soul and body, of which the first is the better, the body is the inferior; wisdom belongs to the better part, and the chief evil belongs to the worse part and is the worst of all. As the best thing of all in the soul is wisdom, so the worst in the body is suffering. Therefore just as bodily pain is the chief evil, wisdom is the chief good of the soul, that is with the wise man; and nothing else can be compared with it.
[Footnote: Aulus Cornelius Celsus, a Roman physician, known as the Roman Hippocrates, probably contemporary with Augustus. Only his eight Books ‘De Medicina’, are preserved. The earliest editions are: Cornelius Celsus, de medicina libr. VIII., Milan 1481 Venice 1493 and 1497.]
Taken from The Notebooks of Leonardo da Vinci edited by Jean Paul Richter, 1880.