The Holy Trinity is
yet has been written about here:
[* = I’ve even read it!]
Ancient (up to AD 500)
Augustine of Hippo. On the Trinity. This is St. Augustine’s book-length work on the Holy Trinity.
—. Sermon 52 (#2 of those on the NT). St. Augustine sets out concisely the teaching on the Holy Trinity in ways that would makes sense to his congregation. I haven’t read it, but I’ve read all about it in Hall’s book, cited below.
*Basil the Great. On the Holy Spirit. In this spirited (ha!) treatise, St. Basil defends the deity of the Son and the Spirit and discusses the work of the Person of the Holy Spirit.
*Gregory of Nazianzus. Theological Orations. In clear, logical terms, St. Gregory sets out the orthodox belief about the Holy Trinity, taking the Incarnation as his starting point.
Gregory of Nyssa. On the Holy Trinity.
*Boethius. Trinity Is One God not Three Gods.
*John of Damascus. On the Orthodox Faith. Book 1, Chapter 8 is about the Holy Trinity.
Thomas Aquinas. Summa Theologica. Prima Pars, qq. 27-43 deal with the Holy Trinity. It’s complex and Aristotelian.
Modern (1500 to the present)
*Calvin, John. Institutes of the Christian Religion. Book 1, Ch. 13. Here Calvin sets out the basic boundaries of Trinitarian thought and deals with certain heresies.
*Hall, Christopher A. Learning Theology with the Church Fathers. In this book, Hall presents the teachings of the Fathers on various major theological issues, dealing with St. Gregory of Nazianzus and St. Augustine of Hippo on the Trinity on pp. 53-82.
*Humphrey, Edith M. Ecstasy and Intimacy: When the Holy Spirit Meets the Human Spirit. Using Trinitarian theology as the background, Humphrey sets out from technical discussions into the realm of “mystical” or “spiritual” theology and Christian “spirituality”.
*Lewis, C.S. Mere Christianity. In the third section of this classic exposition of the Christian faith, “Beyond Personality”, Dr. Lewis discusses the doctrine of the Most Holy Trinity.
*Tozer, A.W. The Knowledge of the Holy. This penetrating yet “simple” book includes a chapter “The Trinity”.
*Volf, Miroslav. Exclusion & Embrace. Pp. 167-190 deal with the Trinity and gender identity in a helpful and incisive way.
—. After Our Likeness: The Church As the Image of the Trinity. I have read most of this book wherein Volf engages with Zizioulas (below) and Ratzinger (aka Benedict XVI) and seeks to move from Triadology to ecclesiology for free church traditions.
*Zizioulas, John D. Being As Communion. Zizioulas gives a brilliant discussion of the Greek fathers and their contribution to theology and our understanding of the Holy Trinity as well as its ramifications for our lives today.
Now the Catholic Faith is this, / that we worship one God in Trinity, and the Trinity in Unity; Neither confusing the Persons, / nor dividing the Substance. For there is one Person of the Father, another of the Son, / another of the Holy Ghost; But the Godhead of the Father, and of the Son, and of the Holy Ghost is all one, / the glory equal, the majesty co-eternal. Such as the Father is, such is the Son, / and such is the Holy Ghost; The Father uncreated, the Son uncreated, the Holy Ghost uncreated; The Father infinite, the Son infinite, the Holy Ghost infinite; The Father eternal, the Son eternal, the Holy Ghost eternal; And yet there are not three eternals, but one eternal; As also there are not three uncreated, nor three infinites, / but one infinite, and one uncreated. So likewise the Father is almighty, the Son almighty, / the Holy Ghost almighty; And yet there are not three almighties, but one almighty. So the Father is God, the Son God, the Holy Ghost God; And yet there are not three Gods, / but one God.
-from the so-called “Creed of St. Athanasius”