His main argument is based on the necessity of prayer. “Why,” he asks, “is that perseverance asked for from God, if it is not given by God? Is it a mocking petition inasmuch as that is asked of Him which it is known He does not give, but, although He gives it not, is in man’s power?... Or is not that perseverance, perchance, asked for from Him? He who says this, is not to be rebuked by my arguments, but must be overwhelmed with the prayers of the saints. Is there indeed one among them who do not ask for themselves from God that they may persevere in Him, when in that very prayer which is called the Lord’s—because the Lord taught it—whenever it is prayed by the saints, scarcely anything else is understood to be prayed for but perseverance?”(396) He then proceeds to show, in accordance with St. Cyprian’s little treatise On the Lord’s Prayer, that the seven petitions of the “Our Father” are all prayers for perseverance, and concludes as follows: “Truly in this matter let not the Church look for laborious disputations, but consider her own daily prayers. She prays that the unbelieving may believe; therefore God converts to the faith. She prays that believers may persevere; therefore God gives perseverance to the end.”(397) And again: “For who is there that would groan with a sincere desire to receive what he prays for from the Lord, if he thought that he received it from himself and not from the Lord?”(398) c) From this teaching flows a corollary of great practical importance, to wit: The grace of final perseverance cannot be merited by good works, but it can be obtained by pious and unremitting prayer. “This gift of God,” says St. Augustine, speaking of final perseverance, “may be obtained suppliantly [by prayer], but when it has been given, it cannot be lost contumaciously.”(399) And again: “Since it is manifest that God has prepared some things to be given even to those who do not pray for them, such as the beginning of faith, and other things not to be given except to those who pray for them, such as perseverance unto the end, certainly he who thinks that he has this latter from himself, does not pray to obtain it.”(400) Between merit (_meritum_) and prayer (_oratio, preces_) there is this great difference, that merit appeals to God’s justice, prayer to His mercy. If man were able to merit final perseverance by good works (_meritum de condigno_), God would be in justice bound to give him this precious grace. But this is plainly incompatible with the Catholic conception of final perseverance.