I have from an early age abjured the use of meat, and the time will come when men such as I will look upon the murder of animals as they now look upon the murder of men.

It is useful to constantly observe, note, and consider.

The study of what is excellent is food for the mind and body.

Drawing is based upon perspective, which is nothing else than a thorough knowledge of the function of the eye.

He who can copy can do.

The discovery of a good wine is increasingly better for mankind than the discovery of a new star.

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.