Light is the chaser away of darkness. Shade is the obstruction of light. Primary light is that which falls on objects and causes light and shade. And derived lights are those portions of a body which are illuminated by the primary light. A primary shadow is that side of a body on which the light cannot fall.

Painting is concerned with all the 10 attributes of sight; which are: Darkness, Light, Solidity and Colour, Form and Position, Distance and Propinquity, Motion and Rest.

Darkness is absence of light. Shadow is diminution of light.

The boundaries of bodies are the least of all things. The proposition is proved to be true, because the boundary of a thing is a surface, which is not part of the body contained within that surface; nor is it part of the air surrounding that body, but is the medium interposted between the air and the body, as is proved in its place.

To any white body receiving the light from the sun, or the air, the shadows will be of a bluish cast.

Study the science of art. Study the art of science. Develop your senses- especially learn how to see. Realize that everything connects to everything else.