6 These verily are they who are entrusted with the pangs of spiritual travail and the birth which comes through baptism: by their means we put on Christ, and are buried with the Son of God, and become members of that blessed Head. Wherefore they might not only be more justly feared by us than rulers and kings, but also be more honored than parents; since these begot us of blood and the will of the flesh, but the others are the authors of our birth from God, even that blessed regeneration which is the true freedom and the sonship according to grace. The Jewish priests had authority to release the body from leprosy, or, rather, not to release it but only to examine those who were already released, and you know how much the office of priest was contended for at that time. But our priests have received authority to deal, not with bodily leprosy, but spiritual uncleanness— not to pronounce it removed after examination, but actually and absolutely to take it away. Wherefore they who despise these priests would be far more accursed than Dathan and his company, and deserve more severe punishment. For the latter, although they laid claim to the dignity which did not belong to them, nevertheless had an excellent opinion concerning it, and this they evinced by the great eagerness with which they pursued it; but these men, when the office has been better regulated, and has received so great a development, have displayed an audacity which exceeds that of the others, although manifested in a contrary way. For there is not an equal amount of contempt involved in aiming at an honor which does not pertain to one, and in despising such great advantages, but the latter exceeds the former as much as scorn differs from admiration. What soul then is so sordid as to despise such great advantages? None whatever, I should say, unless it were one subject to some demoniacal impulse. For I return once more to the point from which I started: not in the way of chastising only, but also in the way of benefiting, God has bestowed a power on priests greater than that of our natural parents. The two indeed differ as much as the present and the future life. For our natural parents generate us unto this life only, but the others unto that which is to come. And the former would not be able to avert death from their offspring, or to repel the assaults of disease; but these others have often saved a sick soul, or one which was on the point of perishing, procuring for some a milder chastisement, and preventing others from falling altogether, not only by instruction and admonition, but also by the assistance wrought through prayers. For not only at the time of regeneration, but afterwards also, they have authority to forgive sins. “Is any sick among you?” it is said, “let him call for the elders of the Church and let them pray over him, anointing him with oil in the name of the Lord. And the prayer of faith shall save the sick, and the Lord will raise him up: and if he have committed sins they shall be forgiven him.” Again: our natural parents, should their children come into conflict with any men of high rank and great power in the world, are unable to profit them: but priests have reconciled, not rulers and kings, but God Himself when His wrath has often been provoked against them.
Well! After this will any one venture to condemn me for arrogance? For my part, after what has been said, I imagine such religious fear will possess the souls of the hearers that they will no longer condemn those who avoid the office for arrogance and temerity, but rather those who voluntarily come forward and are eager to obtain this dignity for themselves. For if they who have been entrusted with the command of cities, should they chance to be wanting in discretion and vigilance, have sometimes destroyed the cities and ruined themselves in addition, how much power think you both in himself and from above must he need, to avoid sinning, whose business it is to beautify the Bride of Christ?
Source: On the Priesthood (New Advent)