Just as a well-filled day brings blessed sleep, so a well-employed life brings a blessed death.

Medicine is the restoration of discordant elements; sickness is the discord of the elements infused into the living body.

If you throw a stone in a pond... the waves which strike against the shores are thrown back towards the spot where the stone struck; and on meeting other waves they never intercept each other's course... In a small pond one and the same stroke gives birth to many motions of advance and recoil.

Make yourself a master of perspective, then acquire perfect knowledge of the proportions of men and other animals.

Whatever you do in life, if you want to be creative and intelligent, and develop your brain, you must do everything with the awareness that everything, in some way, connects to everything else.

It's not enough that you believe what you see. You must also understand what you see.

Affective gestures pointing to things near either in time or space should be made with the hand not very far from the body of the person pointing; and if these things are distant, the hand of the painter should be more extended and the face turned toward the person to whom he is addressing the demonstration.