Every action needs to be prompted by a motive. To know and to will are two operations of the human mind. Discerning, judging, deliberating are acts of the human mind.

The human foot is a masterpiece of engineering and a work of art.

The boundaries of bodies are the least of all things.

The body of the earth is of the nature of a fish... because it draws water as its breath instead of air.

All objects transmit their image to the eye in pyramids and the nearer to the eye these pyramids are intersected the smaller will the image appear of the objects which cause them.

Of several bodies, all equally large and equally distant, that which is most brightly illuminated will appear to the eye nearest and largest.

Poor is the pupil who does not surpass his master.