1 Corinthians 2:7

But we speak the wisdom of God in a mystery. (1.) This is a Hebraism for "the wisdom of the mystery." that great secret of the Divine counsel, about the Incarnation of the Word, and the redemption of man by Christ, which cannot be attained to by man by any effort of reason no, nor yet by the angels, as is clear from Eph. v. 4, 5. Hence, in 1 Tim. iii. 16, this wisdom of the mystery is called the great mystery of godliness. So Theophylact, Ambrose, Œcumenius, commenting on this verse, and Jerome and Leo Castrius on Isa. lxiv; also S. Leo. (2.) We may understand this wisdom to be concerned with the greatness of the glory of the Blessed, for this was the end of the Incarnation and suffering of the Word.

Secondly, it is simpler to connect the words "in a mystery" with "we speak" rather than with "wisdom." Then the meaning is, we speak secretly and to a few, viz., those who are perfect, the spiritual, of this deeper and more hidden wisdom. Hence Ephrem and Tertullian render the passage: "We speak of the wisdom of God in secret." Hence also S. Dionysius and others have written books on mystic theology.