Strom 1.1.15.5 - 16.1 "For not only for the Hebrews and those that are under the law," according to the apostle, "is it right to become a Jew, but also a Greek for the sake of the Greeks, that we may gain all." Also in the Epistle to the Colossians he writes, "Admonishing every man, and teaching every man in all wisdom, that we may present every man perfect in Christ."
οὐ γὰρ μόνον δι' Ἑβραίους καὶ τοὺς ὑπὸ νόμον κατὰ τὸν ἀπόστολον εὔλογον Ἰουδαῖον γενέσθαι, ἀλλὰ καὶ διὰ τοὺς Ἕλληνας Ἕλληνα, ἵνα πάντας κερδάνωμεν. κἀν τῇ πρὸς Κολασσαεῖς ἐπιστολῇ νουθετοῦντες γράφει πάντα ἄνθρωπον καὶ διδάσκοντες ἐν πάσῃ σοφίᾳ, ἵνα παραστήσωμεν πάντα ἄν θρωπον τέλειον ἐν Χριστῷ
I don't care what 'textual critics' will say, at least one possibility is that Clement originally thought that the reading was:
For not only for the Hebrews and those that are under the law is it right to become a Jew, but also a Greek for the sake of the Greeks, that we may gain all, admonishing every man, and teaching every man in all wisdom, that we may present every man perfect in Christ
Compare the two citations as they stand now. First the beginning of Clement's reference and 1 Corinthians 9:19 - 22:
οὐ γὰρ μόνον δι' Ἑβραίους καὶ τοὺς ὑπὸ νόμον κατὰ τὸν ἀπόστολον εὔλογον Ἰουδαῖον γενέσθαι, ἀλλὰ καὶ διὰ τοὺς Ἕλληνας Ἕλληνα, ἵνα πάντας κερδάνωμεν
καὶ ἐγενόμην τοῖς Ἰουδαίοις ὡς Ἰουδαῖος, ἵνα Ἰουδαίους κερδήσω· τοῖς ὕπο νόμον ὡς ὑπὸ νόμον, μὴ ὢν αὐτὸς ὑπὸ νόμον, ἵνα τοὺς ὑπὸ νόμον κερδήσω· τοῖς ἀνόμοις ὡς ἄνομος, μὴ ὢν ἄνομος θεοῦ ἀλλ’ ἔννομος Χριστοῦ, ἵνα κερδάνω τοὺς ἀνόμους· ἐγενόμην τοῖς ἀσθενέσιν ἀσθενής, ἵνα τοὺς ἀσθενεῖς κερδήσω· τοῖς πᾶσιν γέγονα πάντα, ἵνα πάντως τινὰς σώσω. πάντα δὲ ποιῶ διὰ τὸ εὐαγγέλιον, ἵνα συγκοινωνὸς αὐτοῦ γένωμαι.
To the Jews I became like a Jew, to win the Jews. To those under the law I became like one under the law (though I myself am not under the law), so as to win those under the law. To those not having the law I became like one not having the law (though I am not free from God’s law but am under Christ’s law), so as to win those not having the law. To the weak I became weak, to win the weak. I have become all things to all people so that by all possible means I might save some. I do all this for the sake of the gospel, that I may share in its blessings.
There is an uncanny resemblance to the structure of the whole passage cited by Clement it just substitutes the concept of 'the gospel' for 'making everyone perfect.' And now the second part of the citation and Colossians 1:28:
πάντα ἄνθρωπον καὶ διδάσκοντες ἐν πάσῃ σοφίᾳ, ἵνα παραστήσωμεν πάντα ἄνθρωπον τέλειον ἐν Χριστῷ
πάντα ἄνθρωπον καὶ διδάσκοντες πάντα ἄνθρωπον ἐν πάσῃ σοφίᾳ, ἵνα παραστήσωμεν πάντα ἄνθρωπον τέλειον ἐν Χριστῷ·
dating back to conversations with his grandfather, Gaston Frank. "He said we represent one of the last descendants of the Frankist Jewish faith in the world," he muses. "I grew up thinking that our family was something like the Last of the Mohicans."