The soul is subject to health and disease, just as is the body. The health and disease of both . . . undoubtedly depend upon beliefs and customs, which are peculiar to mankind.

The more we desire for that which is superfluous, the more we meet with difficulties; our strength and possessions are spent in unnecessary things, and are wanting when required for that which is necessary.

The people who are abroad are all those that have no religion, neither one based on speculation nor one received by tradition. Such are the extreme Turks that wander about in the north, the Kushites who live in the south, and those in our country who are like these. I consider these as irrational beings, and not as human beings; they are below mankind, but above monkeys, since they have the form and shape of man, and a mental faculty above that of the monkey.

He who does not understand that a dead lion is more alive than a living dog will remain a dog.

Teach thy tongue to say 'I do not know,' and thou shalt progress.

God who preceded all existence is a refuge.

How individuals of the same species surpass each other in these sensations and in other bodily faculties is universally known, but there is a limit to them, and their power cannot extend to every distance or to every degree.