On the Trinity in the context of "Logos"

Augustine of Hippo (/ɔːˈɡʌstɪn/ aw-GUST-in, US also /ˈɔːɡəstiːn/ AW-gə-steen; Latin: Aurelius Augustinus Hipponensis; 13 November 354 – 28 August 430) was a theologian and philosopher, the bishop of Hippo Regius from Thagaste in Numidia Cirtensis, (present-day Souk Ahras, Algeria). His writings deeply influenced the development of Western philosophy and Western Christianity, and he is viewed as one of the most important Church Fathers of the Latin Church in the Patristic Period. His many important works include The City of God, On Christian Doctrine, and Confessions.

According to his contemporary, Jerome of Stridon, Augustine "established anew the ancient Faith". In his youth he was drawn to the Manichaean faith, and later to the Hellenistic philosophy of Neoplatonism. After his conversion to Christianity and baptism in 386, Augustine developed his own approach to philosophy and theology, accommodating a variety of methods and perspectives. Believing the grace of Christ was indispensable to human freedom, he helped formulate the doctrine of original sin and made significant contributions to the development of just war theory. When the Western Roman Empire began to disintegrate, Augustine imagined the Church as a spiritual City of God, distinct from the material Earthly City. The segment of the Church that adhered to the concept of the Trinity as defined by the Council of Nicaea and the Council of Constantinople closely identified with Augustine's On the Trinity.

On the City of God Against the Pagans (Latin: De civitate Dei contra paganos), often called The City of God, is a book of Christian philosophy written in Latin by Augustine of Hippo in the early 5th century AD. Augustine wrote the book to refute allegations that Christianity initiated the decline of Rome and is considered one of his seminal works, standing alongside the Confessions, the Enchiridion, On Christian Doctrine, and On the Trinity. As a work of one of the most influential Church Fathers, The City of God is a cornerstone of Western thought, expounding on many questions of theology, such as the suffering of the righteous, the existence of evil, the conflict between free will and divine omniscience, and the doctrine of original sin.

In Christian theology, perichoresis (from Ancient Greek: περιχώρησις, romanized: perikhōrēsis, lit. 'rotation') is the relationship of the three persons of the triune God (Father, Son, and Holy Spirit) to one another. The term was first used theologically by the Church Fathers. As a noun, the word first appears in the writings of Maximus Confessor (d. 662), but the related verb perichoreo is found earlier in the work of Gregory of Nazianzus (d. 389/90). Gregory used the word to describe the relationship between the divine and human natures of Christ, as did John of Damascus (d. 749), who also extended it to the "interpenetration" of the three persons of the Trinity, and it became a technical term for the latter. "Circumincession" is a Latin-derived term for the same concept. However, the idea was present in Latin Christianity even before the Eastern fathers; this is made explicit by St. Hillary's De Trinitate. Augustine also writes in his De Trinitate (On the Trinity):

The term has been given recent currency by such contemporary writers as Jürgen Moltmann, Miroslav Volf, John Zizioulas, Richard Rohr, and others. Modern authors extend the original usage as an analogy to cover other interpersonal relationships. The term "co(-)inherence" is sometimes used as a synonym.