In this foundational work of Christian theology, Tertullian provides a brilliant and vigorous defence of the Trinity against the teachings of Praxeas. Writing at a time when the early Church was defining its understanding of God’s nature, Tertullian offers a masterful explanation of the relationship between the Father, the Son, and the Holy Spirit. This scholarly edition by Alexander Souter serves as an essential resource for those who wish to understand the roots of Christian orthodoxy and the arguments used by the early Church fathers to combat heresy. Whether you are a student, a pastor, or a layperson with a passion for historical theology, this book invites you to explore the profound mystery of the Godhead through the eyes of one of the most influential thinkers in church history. By engaging with this classic text, you will gain a deeper appreciation for the scriptural foundations of the Trinity and the enduring clarity of the faith once delivered to the saints. It remains a vital study for anyone seeking to anchor their understanding of God in the intellectual tradition of the ancient Church.