Thomas Aquinas

Then he continues: which now, namely, the mystery, is made manifest, i.e., about the conversion of the gentiles, through the writings of the prophets, i.e., as the prophets foretold. Hence, he says in Ephesians: this mystery was not made known to the sons of men in other generations as it has now been revealed to his holy apostles and prophets by the Spirit, that is, that the gentiles are fellow heirs, members of the same body (Eph 3:5ff.). But it was made known by fulfillment of a work proceeding from God's command. …

Commentary on Romans ↗