Nature never breaks her own laws. - Leonardo da Vinci

These rules will enable you to have a free and sound judgment; since good judgment is born of clear understanding, and a clear understanding comes of reasons derived from sound rules, and sound rules are the issue of sound experience — the common mother of all the sciences and arts. Hence, bearing in mind the precepts of my rules, you will be able, merely by your amended judgment, to criticise and recognise every thing that is out of proportion in a work, whether in the perspective or in the figures or any thing else.

"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

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