St. Augustine of Hippo, born on November 13, 354, in Tagaste (modern-day Algeria), is one of the most influential theologians and philosophers in Christian history. Raised by a Christian mother, Monica, Augustine initially led a life marked by hedonism and philosophical exploration, particularly in the teachings of Manichaeism and Neoplatonism. His profound spiritual journey culminated in his conversion to Christianity in 386, significantly influenced by the preaching of St. Ambrose and the powerful words of the Scriptures.

Ordained a priest in 391 and later becoming the Bishop of Hippo in 396, Augustine devoted his life to preaching, teaching, and defending the faith against heresies. He is best known for his writings, including "Confessions," an autobiographical work detailing his conversion, and "The City of God," which addresses the relationship between Christianity and society. 

Augustine's theological contributions, particularly on original sin, grace, and free will, laid the groundwork for much of Western Christian thought. He died on August 28, 430, and was canonized as a saint. His feast day is celebrated on August 28, and he is recognized as a Doctor of the Church. His legacy continues to inspire and shape Christian doctrine and philosophy to this day.