7 For let the best artificer be himself the critic of his own designs, and let his performances be determined to be good or poor, according as the mind which designed them gives sentence upon them. But let him not even consider the opinion, so erroneous and inartistic, of the outside world. Let, therefore, the man who undertakes the strain of teaching never give heed to the good opinion of the outside world, nor be dejected in soul on account of such persons; but laboring at his sermons so that he may please God, (For let this alone be his rule and determination, in discharging this best kind of workmanship, not acclamation, nor good opinions,) if, indeed, he be praised by men, let him not repudiate their applause, and when his hearers do not offer this, let him not seek it, let him not be grieved. For a sufficient consolation in his labors, and one greater than all, is when he is able to be conscious of arranging and ordering his teaching with a view to pleasing God.
Source: On the Priesthood (New Advent)