Just as iron rusts from disuse, and stagnant water putrefies, or when cold turns to ice, so our intellect wastes unless it is kept in use.

The fox when it sees a flock of herons or magpies or birds of that kind, suddenly flings himself on the ground with his mouth open to look as he were dead; and these birds want to peck at his tongue, and he bites off their heads.

Happy will they be who lend ear to the words of the dead.

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.

The first of all simple colours is White ... We shall set down White for the representative of light, without which no colour can be seen; Yellow for the earth; Green for water; Blue for air; Red for fire; and Black for total darkness.

We must doubt the certainty of everything which passes through the senses, but how much more ought we to doubt things contrary to the senses, such as the existence of God and the soul.

Music cannot be called otherwise than the sister of painting, for she is dependent upon hearing, a sense second to sight, and her harmony is composed of the union of its proportional parts sounded simultaneously, rising and falling in one or more harmonic rhythms.