On the doctrine that Dreams are sent from God, Books 1-2 (1.51-1.55)

And those will obtain the second place who are not allured indeed to enjoy the sacred table, but who nevertheless refresh their souls with its odours; for they will be excited by the fragrances of virtue like those languid invalids who, because they are not as yet able to take solid food, nevertheless feed on the smell of such viands as the sons of the physicians prepare as a sort of remedy for their impotency.

Therefore, having left the land of the Chaldaeans, Terah is said to have migrated to Charran; bringing with him his son Abraham and the rest of his household who agreed with him in opinion, not in order that we might read in the account of the historical chronicles that some men had become emigrants, leaving their native country and becoming inhabitants of a foreign land as if it were their own country, but in order that a lesson of the greatest importance to life and full of wisdom, and adapted to man alone, might not be neglected.

And what is the lesson? The Chaldaeans are great astronomers, and the inhabitants of Charran occupy themselves with the topics relating to the external senses. Therefore the sacred account says to the investigator of the things of nature, why are you inquiring about the sun, and asking whether he is a foot broad, whether he is greater than the whole earth put together, or whether he is even many times as large? And why are you investigating the causes of the light of the moon, and whether it has a borrowed light, or one which proceeds solely from itself? Why, again, do you seek to understand the nature of the rest of the stars, of their motion, of their sympathy with one another, and even with earthly things?

And why, while walking upon the earth do you soar above the clouds? And why, while rooted in the solid land, do you affirm that you can reach the things in the sky? And why do you endeavour to form conjectures about matters which cannot be ascertained by conjecture? And why do you busy yourself about sublime subjects which you ought not to meddle with? And why do you extend your desire to make discoveries in mathematical science as far as the heaven? And why do you devote yourself to astronomy, and talk about nothing but high subjects? My good man, do not trouble your head about

How, then, will you find out what you want, even if you are successful? Go with full exercise of your intellect to Charran, that is, to the trench which is dug, into the holes and caverns of the body, and investigate the eyes, the ears, the nostrils, and the other organs of the external senses; and if you wish to be a philosopher, study philosophically that branch which is the most indispensable and at the same time the most becoming to a man, and inquire what the faculty of sight is, what hearing is, what taste, what smell, what touch is, in a word, what is external sense; then seek to understand what it is to see, and how you see; what it is to hear, and how you hear; what it is to smell, or to taste, or to touch, and how each of these operations is ordinarily effected.