6 He, then, who has learned [these things], and known all the angels and their causes, is rendered invisible and incomprehensible to the angels and all the powers, even as Caulacau also was. And as the son was unknown to all, so must they also be known by no one; but while they know all, and pass through all, they themselves remain invisible and unknown to all; for, “Do you,” they say, “know all, but let nobody know you.” For this reason, persons of such a persuasion are also ready to recant [their opinions], yea, rather, it is impossible that they should suffer on account of a mere name, since they are like to all. The multitude, however, cannot understand these matters, but only one out of a thousand, or two out of ten thousand. They declare that they are no longer Jews, and that they are not yet Christians; and that it is not at all fitting to speak openly of their mysteries, but right to keep them secret by preserving silence.
Source: Adversus haereses (New Advent)