It is useful to constantly observe, note, and consider.

The most beautiful words of love are told in silence for a look.

Those who, in debate, appeal to their qualifications, argue from memory, not from understanding.

If a man has a tent made of linen of which the apertures have all been stopped up, and be it twelve bracchia across (over twenty-five feet) and twelve in depth, he will be able to throw himself down from any height without sustaining injury. [His concept of the parachute.]

O painter skilled in anatomy, beware lest the undue prominence of the bones, sinews and muscles cause you to become a wooden painter from the desire to make your nude figures reveal all.

How many emperors and how many princes have lived and died and no record of them remains, and they only sought to gain dominions and riches in order that their fame might be ever-lasting.

If you put on more clothes as the cold increases, it will have no power to hurt you. Let us hope that.