I now begin to speak of a mystery which is altogether above the power of any human being (including myself) to express in words. Indeed, when I begin to reflect on the triune God [God in three persons: Father, Son, and Holy Spirit], I am conscious of the distance between my mind and the God of whom it is thinking. Therefore I call upon the Lord our God for help to understand and explain my subject and I beg His pardon wherever I go astray.

—Augustine, The Trinity, 5.1.1