One day the world will look upon research upon animals as it now looks upon research on human beings.

Perspective is nothing more than a rational demonstration applied to the consideration of how objects in front of the eye transmit their image to it, by means of a pyramid of lines. The Pyramid is the name I apply to the lines which, starting from the surface and edges of each object, converge from a distance and meet in a single point.

To make a perfume, take some rose water and wash your hands in it, then take a lavender flower and rub it with your palms, and you will achieve the desired effect

A painter should begin every canvas with a wash of black, because all things in nature are dark except where exposed by the light.

I say that the power of vision extends through the visual rays to the surface of non-transparent bodies, while the power possessed by these bodies extends to the power of vision.

Instrumental or mechanical science is the noblest and above all others, the most useful.

Life well spent is long.