37 To go on to what he says, "that a bishop should be 'teachable,'" adding, "But he is teachable who is gentle and meek to learn; for a bishop ought not only to teach, but to learn as well, since he is indeed the better teacher who daily grows and advances by learning better things;" — in these words assuredly the holy man, endowed with pious charity, sufficiently points out that we should not hesitate to read his letters in such a sense, that we should feel no difficulty if the Church should afterwards confirm what had been discovered by further and longer discussions; because, as there were many things which the learned Cyprian might teach, so there was still something which the teachable Cyprian might learn.
But the admonition that he gives us, "that we should go back to the fountain, that is, to apostolic tradition, and thence turn the channel of truth to our times," is most excellent, and should be followed without hesitation. It is handed down to us, therefore, as he himself records, by the apostles, that there is "one God, and one Christ, and one hope, and one faith, and one Church, and one baptism." Since then we find that in the times of the apostles themselves there were some who had not the one hope, but had the one baptism, the truth is so brought down to us from the fountain itself, that it is clear to us that it is possible that though there is one Church, as there is one hope, and one baptism, they may yet have the one baptism who have not the one Church; just as even in those early times it was possible that men should have the one baptism who had not the one hope.
For how had they one hope with the holy and the just, who used to say, "Let us eat and drink, for tomorrow we die," asserting that there was no resurrection of the dead? And yet they were among the very men to whom the same apostle says, "Was Paul crucified for you? Or were you baptized in the name of Paul?" For he writes most manifestly to them, saying, "How say some among you that there is no resurrection of the dead?"
Source: On Baptism, Against the Donatists (New Advent)