What was Augustine's conversion experience?

As with many young men, Augustine led a rather dissolute lifestyle. He lacked purpose and direction and had too strong an attachment to the things of this world. Notoriously, he openly lived with a mistress, by whom he had an illegitimate son, Adeodatus. Augustine's mistress converted to Christianity, ending their illicit relationship. However, Augustine himself continued to pursue pleasure despite desiring holiness at the same time.
Inspired by the example of St. Anthony of the Desert, Augustine made strenuous efforts to open his heart to the Christian message. While praying in a garden one day and crying bitterly over his attachment to sin, Augustine suddenly heard a faint voice. The voice appeared to be speaking to him directly, saying "Tolle, lege," which is Latin for "Take up and read." Augustine did as he was instructed and opened the letters of St. Paul at random. The passage he found, in Romans 13:13–14, spoke to his situation directly:

Let us walk honestly, as in the day; not in rioting and drunkenness, not in chambering and wantonness, not in strife and envying. But put ye on the Lord Jesus Christ, and make not provision for the flesh, to fulfill the lusts thereof.

The word of God had spoken. Augustine abandoned his life of sin to embrace the teachings of Christ. At the Easter Vigil in 388 CE, Augustine was formally received into the Church and baptized alongside Adeodatus by St. Ambrose, the bishop of Milan.