[79] [cap.19] Those who investigate the nature of things as they actually exist, and who conduct their examinations of each individual matter in no negligent manner, behave very like those men who dig wells; for they also are seeking springs in an obscure place. And all men have one common desire, to find something to drink. But some men’s nature is to be nourished by the food of the soul, and that of others by the food of the body.