but it is necessary to employ all these things not so much for whatever objects can possibly be effected, but for those that are best; for the sight can perceive all colours and all shapes; but still it ought to behold only things worthy of light, and not of darkness. Again, the ear can receive all kinds of sounds; but some it ought to disregard; for myriads of the things that are said are disgraceful. Nor, O foolish and arrogant man, because nature has given you the faculty of taste, ought you to fill yourself insatiably with everything, like a cormorant; for there are many things not merely among such as are nutritious, but of those which are exceedingly so, which have, nevertheless, produced diseases accompanied with great suffering.
 Nor does it follow that, because for the sake of the perpetuation of your race you have been endowed with the powers of generation, you ought to pursue pollutions and adulteries and other impure connections; but only such as, in a legitimate manner, engender and propagate the race of mankind. Nor, because you have been made endowed with a mouth and a tongue and the organs of speech, ought you to say everything and to reveal what ought not to be spoken, for there are times when to hold one’s peace is useful. And, in my opinion, those
 
who have learnt to speak have also learnt to be silent, the same capacity teaching a man both lines of conduct. But those men who relate what they ought not, do not display the faculty of eloquence, but the weakness of their faculty of silence. On which account we labour to bind each of the mouthpieces of the senses before-mentioned with the imperishable bonds of temperance. "For whatever is not bound with a bond," says Moses, in another passage, "is impure," Numbers xix. 15. as if the cause of its unhappiness was the fact of the parts of the soul being relaxed and open and dissolved; but that the fact of their being compacted and tightly bound together contributed to goodness and soundness of life and reason.
He, therefore, curses the godless and impious Cain with deserved curses; because, having opened the caverns of this concrete creature, he opened his mouth for all external things, praying to receive them in an insatiable manner and to contain them, to the utter destruction of the God-loving doctrine, Abel.
 "On this account shall he cultivate the earth;" Genesis iv. 12. he does not say, "He shall become a farmer." For every farmer is an artist, because farming is an art. But any of the common people are cultivators of the earth, giving their service to provide themselves with necessaries, without any skill. These men, then, as they have no superintendent in all that they do, do much harm; and whatever they do well they do by chance, and not in accordance with reason. But the works of farmers, which are performed according to knowledge, are all of them, of necessity, useful.
 On this account it is that the law-giver has attributed to the just Noah the employment of a farmer; Genesis ix. 90. showing by this that, like a good farmer, the virtuous man eradicates in the wild wood all the mischievous young saplings which have been planted by the passions or by the vices, but leaves untouched all those which bear fruit, and which may act instead of a wall and prove a firm defence for the soul. And, again, among the trees capable of cultivation he manages them in different ways, and not all in the same way: pruning some and adding props to others, training some so as to increase their size, and cutting down others so as to keep them dwarf.