3 Do ye not suppose that the wicked themselves laugh at those who are of like characters to themselves, and condemn them? For since God has placed within us a tribunal which cannot be bribed nor ever utterly destroyed, even though we come to the very lowest depth of vice; therefore even the wicked themselves give sentence against themselves, and if one call them that which they are, they are ashamed, they are angry, they say that it is an insult. Thus they condemn what they do, even if not by their deeds, yet by their words, by their conscience, nay rather even by their deeds. For when they carry on their practices out of sight and secretly, they give the strongest proof of the opinion they hold concerning the thing itself. For wickedness is so manifest, that all men are its accusers, even those who follow after it, while such is the quality of virtue, that it is admired even by those who do not emulate it. For even the fornicator will praise chastity, and the covetous will condemn injustice, and the passionate will admire patience, and blame quarrelsomeness, and the wanton [will blame] wantonness.
How then (you say) does he pursue these things? From excessive indolence, not because he judges it good; otherwise he would not have been ashamed of the thing itself, nor would he have denied it when another accused him. Nay many when caught, not enduring the shame, have even hanged themselves. So strong is the witness within us in behalf of what is good and becoming. Thus what is good is brighter than the sun, and the contrary more unsightly than anything.
Source: Homilies on the Epistle to the Hebrews (New Advent)