Leonardo da Vinci

Thou, O God, sellest us all benefits, at the cost of our toil.... As a day well spent makes sleep seem pleasant, so a life well employed makes death pleasant. A life well spent is long."

"the painter strives and competes with nature,"

inward purpose and outward expression

"There is nothing in all nature without its reason," he wrote. "If you know the reason, you do not need the experience."

A keen desire for knowledge, guiding his action in life, spurred him onward.