Many are they who have a taste and love for drawing, but no talent; and this will be discernible in boys who are not diligent and never finish their … - Leonardo da Vinci

Every body in light and shade fills the surrounding air with infinite images of itself; and these, by infinite pyramids diffused in the air, represent this body throughout space and on every side.

"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

The line has in itself neither matter nor substance and may rather be called an imaginary idea than a real object; and this being its nature it occupies no space. Therefore an infinite number of lines may be conceived of as intersecting each other at a point, which has no dimensions and is only of the thickness (if thickness it may be called) of one single line.