The Art of Poetry: To the Pisos (419)

As a crier who collects the crowd together to buy his goods, so a poet rich in land, rich in money put out at interest, invites flatterers to come [and praise his works] for a reward. But if he be one who is well able to set out an elegant table,[*] and give security for a poor man, and relieve him when entangled in gloomy law-suits; I shall wonder if with his wealth he can distinguish a true friend from a false one. You, whether you have made, or intend to make, a present to any one, do not bring him full of joy directly to your finished verses: for then he will cry out, "Charming, excellent, judicious," he will turn pale; at some parts he will even distill the dew from his friendly eyes; he will jump about; he will beat the ground [with ecstasy]. As those who mourn at funerals for pay, do and say more than those that are afflicted from their hearts; so the sham admirer is more moved than he that praises with sincerity. Certain kings are said to ply with frequent bumpers, and by wine make trial of a man whom they are sedulous to know, whether he be worthy of their friendship or not. Thus, if you compose verses, let not the fox's concealed intentions impose upon you.

If you had recited any thing to Quintilius, he would say, "Alter, I pray, this and this:" if you replied, you could do it no better, having made the experiment twice or thrice in vain; he would order you to blot out, and once more apply to the anvil your ill-formed verses: if you choose rather to defend than correct a fault, he spent not a word more nor fruitless labor, but you alone might be fond of yourself and your own works, without a rival. A good and sensible man will censure spiritless verses, he will condemn the rugged, on the incorrect he will draw across a black stroke with his pen; he will lop off ambitious [and redundant] ornaments; he will make him throw light on the parts that are not perspicuous; he will arraign what is expressed ambiguously; he will mark what should be altered; [in short,] he will be an Aristarchus:[*] he will not say, "Why should I give my friend offense about mere trifles?" These trifles will lead into mischiefs of serious consequence, when once made an object of ridicule, and used in a sinister manner.