The mind that engages in subjects of too great variety becomes confused and weakened.

Medicine is the restoration of discordant elements; sickness is the discord of the elements infused into the living body.

A wave is never found alone, but is mingled with as many other waves as there are uneven places in the object where the said wave is produced.

Wood feeds the fire which burns it.

Now do you not see that the eye embraces the beauty of the whole world? It counsels and corrects all the arts of mankind... it is the prince of mathematics, and the sciences founded on it are absolutely certain. It has measured the distances and sizes of the stars it has discovered the elements and their location... it has given birth to architecture and to perspective and to the divine art of painting.

Learning acquired in youth arrests the evil of old age; and if you understand that old age has wisdom for its food, you will so conduct yourself in youth that your old age will not lack for nourishment.

Nature never breaks her own laws.