Aurelius Augustine, commonly known as Saint Augustine, was a Christian theologian and philosopher born in 354 AD in Thagaste, present-day Algeria. He is best known for his influential works, including "Confessions" and "The City of God," which explore themes of faith, morality, and the nature of God. Augustine's thoughts laid the groundwork for much of Western Christianity and philosophy. Augustine's early life was marked by a search for truth, leading him through various beliefs, including Manichaeism and Neoplatonism. He eventually converted to Christianity in 386 AD, profoundly impacting Christian doctrine. His ideas on original sin, grace, and free will continue to be studied and debated in theological circles today.