The solar rays will kindle fire on the earth, by which a thing that is under the sky will be set on fire, and, being reflected by some obstacle, it w… - Leonardo da Vinci

Painting is concerned with all the ten attributes of sight, namely darkness and brightness, substance and colour, form and place, remoteness and nearness, movement and rest; and it is with these attributes that this my small book will be woven, recalling to the painter by what rules and in what way he ought by his art to imitate all things that are the work of nature and the adornment of the world.

He had searched to find a scientific basis for art, and discovered it in the imitation of nature, based on rational experience.

We must doubt the certainty of everything which passes through the senses, but how much more ought we to doubt things contrary to the senses, such as the existence of God and the soul.