"On the Trinity" is a theological work by St. Augustine, written in the early 5th century. In this text, Augustine explores the nature of the Holy Trinity, which consists of God the Father, God the Son, and God the Holy Spirit. He seeks to explain how these three distinct persons coexist as one divine essence. Augustine uses various analogies to clarify the relationship between the Trinity's persons, emphasizing their unity and equality. The work has significantly influenced Christian theology, shaping the understanding of the Trinity in both the Catholic Church and Protestantism.