Ask counsel of him who rules himself well.
An infinite number of men will sell publicly and unhindered things of the very highest price, without leave from the Master of it; while it never was theirs nor in their power; and human justice will not prevent it.
Things that are separate shall be united and acquire such virtue that they will restore to man his lost memory.
Science is the observation of things possible, whether present or past; prescience is the knowledge of things which may come to pass, though but slowly.
There shall be wings! If the accomplishment be not for me, ’tis for some other. The spirit cannot die; and man, who shall know all and shall have wings.
Perspective is a most subtle discovery in mathematical studies, for by means of lines it causes to appear distant that which is near, and large that which is small.
Abbreviators do harm to knowledge and to love.
Whoever despises the high wisdom of mathematics nourishes himself on delusion and will never still the sophistic sciences whose only product is an eternal uproar.
While you are alone you are entirely your own master and if you have one companion you are but half your own, and the less so in proportion to the indiscretion of his behavior.
Those who are enamoured of practice without science are like a pilot who goes into a ship without rudder or compass and never has any certainty of where he is going. Practice should always be based upon a sound knowledge of theory.
If you call painting dumb poetry, the painter may call poetry blind painting.
The limiting surface of one thing is the beginning of another.
Avoid the precepts of those thinkers whose reasoning is not confirmed by experience.
You grow in reputation like bread in the hands of a child.
Avoid studies of which the result dies with the worker.
The art of procreation and the members employed therein are so repulsive, that if it were not for the beauty of the faces and the adornments of the actors and the pent-up impulse, nature would lose the human species.
How painting surpasses all human works by reason of the subtle possibilities which it contains.
Nothing is more apt to deceive us than our own judgment of our work. We derive more benefit from having our faults pointed out by our enemies than from hearing the opinions of friends.
The senses are of the earth, the reason stands apart from them in contemplation.
Whoever in debate quotes authority uses not intellect, but memory.