"Leonardo is a hero of curiosity. He was the preeminent figure in an era that had an unprecedented interest in how things work. Curiosity takes ignorance seriously, and is confident enough to admit when it does not know. It is aware of not knowing, and it sets out to do something about it. The fine quality of this page of investigations presents curiosity as an elegant accomplishment. Leonardo is not prying, nosy or intrusive. His will to discover is organised. He wants to understand. It is not a matter, with him, of finding a stray fact here or there. He wants to know something important, and he has contained his insights in a single, lucid page."
Extract from Art as Therapy by Alain de Botton and John Armstrong