St. Francis of Assisi on the Priesthood

Listen, my brothers: If the Blessed Virgin is so honored, as it is right, since she carried Him in her most holy womb; if the blessed Baptist trembled and did not dare to touch the holy head of God; if the tomb in which He lay for some time is so venerated, how holy, just, and worthy must be the person who touches Him with his hands, receives Him in his heart and mouth, and offers Him to others to be received. This is He Who is now not about to die, but Who is eternally victorious and glorified, upon Whom the angels desire to gaze (1 Pet 1:12).

Look at your dignity, you brothers (who are) priests, and be holy since He is holy (cf. Lev 19:2). And as the Lord God has honored you above all other persons because of this ministry, so you should love, reverence, and honor Him above all others. It is a great misery and a miserable weakness that when you have Him present with you in this way, you concern yourselves with anything else in this entire world.

And since he who is of God listens to the words of God (cf. Jn 8:47), we who have been called more particularly for the divine functions should in consequence not only listen to and do what God says, but we should also guard the (sacred) vessels and other (liturgical) appointments so that we may impress upon ourselves the loftiness of our Creator and our subjec­tion to Him. Therefore, I admonish all my brothers and encourage (them) in Christ that wherever they come upon the written words of God they venerate them so far as they are able.

But if any of the brothers do not wish to observe these things, I do not consider them to be Catholics nor my brothers, and I do not wish to see them or speak with them until they shall have done penance. I say this also of all others who go wandering about with no regard for the discipline of the Rule, for our Lord Jesus Christ gave His life that He might not lose the obedience of the most holy Father. (cf. Phil 2:8)