It is bad if you praise, and worse if you reprove a thing, I mean, if you do not understand the matter well. - Leonardo da Vinci

It is ill to praise, and worse to reprimand in matters that you do not understand.

"There are three classes of people: those who see. Those who see when they are shown. Those who do not see."

Time stays long enough for anyone who will use it.

Poor is the pupil who does not surpass his master

Simplicity is the ultimate sophistication.

Nature is the source of all true knowledge. She has her own logic, her own laws, she has no effect without cause nor invention without necessity

Tell me if anything was ever done... Tell me... Tell me.

A single and distinct luminous body causes stronger relief in the object than a diffused light; as may be seen by comparing one side of a landscape illuminated by the sun, and one overshadowed by clouds, and so illuminated only by the diffused light of the atmosphere.