Lamentations 2:18

Think how great that weeping must be that deserves to be compared with a flood of waters. Whoever so weeps and says with the prophet Jeremiah, "let not the apple of my eye cease," shall straightway find the words fulfilled of him: "mercy and truth are met together; righteousness and peace have kissed each other." If righteousness and truth terrify him, mercy and peace may encourage him to seek salvation.

From these tears those are vastly different that are squeezed out from dry eyes while the heart is hard, and although we cannot believe that these are altogether fruitless (for the attempt to shed them is made with a good intention, especially by those who have not yet been able to attain to perfect knowledge or to be thoroughly cleansed from the stains of past or present sins), yet certainly the flow of tears ought not to be thus forced out by those who have already advanced to the love of virtue, nor should the weeping of the outward person be with great labor attempted, as even if it is produced it will never attain the rich copiousness of spontaneous tears. For it will rather cast down the soul of the suppliant by his endeavors, and humiliate him, and plunge him in human affairs and draw him away from the celestial heights, wherein the awed mind of one who prays should be steadfastly fixed, and will force it to relax its hold on its prayers and grow sick from barren and forced tears.

The Savior also wept over the city of Jerusalem because its inhabitants had not repented; and Peter washed out his triple denial with bitter tears, thus fulfilling the words of the prophet: "rivers of waters run down my eyes." Jeremiah too laments over his impenitent people, saying, "O that my head were waters and my eyes a fountain of tears, that I might weep day and night for … my people!" And farther on he gives a reason for his lamentation: "do not weep for the dead," he writes, "neither bemoan him, but weep bitterly for him that goes away, for he shall return no more." The Jew and the Gentile therefore are not to be bemoaned, for they have never been in the church and have died once for all (it is of these that the Savior says, "Let the dead bury their dead"15); weep rather for those who by reason of their crimes and sins go away from the church and who, suffering condemnation for their faults, shall no more return to it. It is in this sense that the prophet speaks to ministers of the church, calling them its walls and towers and saying to each in turn, "O wall, let tears run down." In this way, it is prophetically implied, you will fulfill the apostolic precept: "Rejoice with them that rejoice and weep with them that weep." By your tears you will melt the hard hearts of sinners until they too weep. However, if they persist in evildoing they will find these words applied to them: "I … planted for you a noble vine, wholly a right seed; how then are you turned into the degenerate plant of a strange vine to me?" He says again, "saying to a stock, you are my father; and to a stone, you have brought me forth; for they have turned their back to me, and not their face." He means they would not turn toward God in penitence but in the hardness of their hearts turned their backs on him to insult him. Wherefore also the Lord says to Jeremiah, "Have you seen that which backsliding Israel has done? She is gone up on every high mountain and under every green tree and there has played the harlot." And I said after she had played the harlot and "had done all these things, Turn to me, but she returned not."19How hardhearted we are, and how merciful God is! Even after our many sins, he urges us to seek salvation. Yet not even so are we willing to turn to better things.