THAT A PAINTER OUGHT TO BE CURIOUS TO HEAR THE OPINIONS OF EVERY ONE
ON HIS WORK.

Certainly while a man is painting he ought not to shrink from
hearing every opinion. For we know very well that a man, though he
may not be a painter, is familiar with the forms of other men and
very capable of judging whether they are hump backed, or have one
shoulder higher or lower than the other, or too big a mouth or nose,
and other defects; and, as we know that men are competent to judge
of the works of nature, how much more ought we to admit that they
can judge of our errors; since you know how much a man may be
deceived in his own work. And if you are not conscious of this in
yourself study it in others and profit by their faults. Therefore be
curious to hear with patience the opinions of others, consider and
weigh well whether those who find fault have ground or not for
blame, and, if so amend; but, if not make as though you had not
heard, or if he should be a man you esteem show him by argument the
cause of his mistake.

On the limitations of painting (533-535)