5. in other ages--Greek, "generations."
      not made known--He does not say, "has not been revealed." Making known by revelation is the source of making known by preaching [BENGEL]. The former was vouchsafed only to the prophets, in order that they might make known the truth so revealed to men in general.
      unto the sons of men--men in their state by birth, as contrasted with those illuminated "by the Spirit" (Greek, "IN the Spirit," compare Re 1:10), Mt 16:17.
      as--The mystery of the call of the Gentiles (of which Paul speaks here) was not unknown to the Old Testament prophets (Isa 56:6, 7; 49:6). But they did not know it with the same explicit distinctness "As" it has been now known (Ac 10:19, 20; 11:18-21). They probably did not know that the Gentiles were to be admitted without circumcision or that they were to be on a level with the Jews in partaking of the grace of God. The gift of "the Spirit" in its fulness was reserved for the New Testament that Christ might thereby be glorified. The epithet, "holy," marks the special consecration of the New Testament "prophets" (who are here meant) by the Spirit, compared with which even the Old Testament prophets were but "sons of men" (Eze 2:3, and elsewhere).

JFB.