Letter 76

Isidore of PelusiumUnknown|isidore pelusium
From: Isidore of Pelusium, monk
To: An inquirer
Date: ~410 AD
Context: Isidore explains the orthodox doctrine of the Trinity against various heresies.

One must never contract the nature of the Godhead in the Jewish manner, reducing it to the Father alone, nor expand it recklessly beyond the holy and consubstantial Trinity. By distinguishing the qualities of the persons and the properties of the hypostases, we then gather them back into one God — because the nature is one, even though the persons are three. This is not a contradiction but a mystery. The Father is God, the Son is God, the Spirit is God — yet there are not three Gods but one. If this strains your understanding, good. A God you could fully comprehend would not be much of a God.

Modern English rendering for readability. See the 19th-century translation or original Latin/Greek for scholarly use.