This work should commence with the conception of man, and should describe the nature of the womb, and how the child inhabits it, and in what stage it dwells there, and the manner of its quickening and feeding, and its growth, and what interval there is between one stage of growth and another, and what thing drives it forth from the body of the mother, and for what reason it sometimes emerges from the belly of its mother before the due time.

Just as a well-filled day brings blessed sleep, so a well-employed life brings a blessed death.

Wood feeds the fire which burns it.

The Bactrian have two humps; the Arabian one only. They are swift in battle and most useful to carry burdens. This animal is extremely observant of rule and measure, for it will not move if it has a greater weight than it is used to, and if it is taken too far it does the same, and suddenly stops and so the merchants are obliged to lodge there.

I roamed the countryside searching for the answers to things I did not understand. Why shells existed on the tops of mountains along with the imprints of coral and plant and seaweed usually found in the sea. Why the thunder lasts a longer time than that which causes it and why immediately on its creation the lightening becomes visible to the eye while thunder requires time to travel. How the various circles of water form around the spot which has been struck by a stone and why a bird sustains itself in the air. These questions and other strange phenomena engaged my thought throughout my life.

He who can copy can do.

There are many occasions when the muscles that form the lips of the mouth move the lateral muscles that are joined to them, and there are an equal number of occasions when these lateral muscles move the lips of this mouth, replacing it where it cannot return of itself, because the function of muscle is to pull and not to push except in the case of the genitals and the tongue.