St. Augustine of Hippo

"Hear my prayer, O Lord; let not my soul faint under thy discipline, nor let me faint in confessing unto thee thy mercies, whereby thou hast saved me from all my most wicked ways till thou shouldst become sweet to me beyond all the allurements that I used to follow. Let me come to love thee wholly, and grasp thy hand with my whole heart that thou mayest deliver me from every temptation, even unto the last. And thus, O Lord, my King and my God, may all things useful that I learned as a boy now be offered in thy service--let it be that for thy service I now speak and write and reckon. For when I was learning vain things, thou didst impose thy discipline upon me: and thou hast forgiven me my sin of delighting in those vanities. In those studies I learned many a useful word, but these might have been learned in matters not so vain; and surely that is the safe way for youths to walk in."
The Confessions Book I, ch. xv, 24