Laudator Temporis Acti

Pierre Hadot, Plotinus or The Simplicity of Vision, tr. Michael Chase (Chicago: University of Chicago Press, 1998), pp. 17-18, quoting Enneads V 1, 8 10-14:

Our doctrines are not novel nor do they date from today: they were stated long ago, but not in an explicit way. Our doctrines are explanations of those older ones, and they use Plato's own words to prove that they are ancient.

καὶ εἶναι τοὺς λόγους τούσδε μὴ καινοὺς μηδὲ νῦν, ἀλλὰ πάλαι μὲν εἰρῆσθαι μὴ ἀναπεπταμένως, τοὺς δὲ νῦν λόγους ἐξηγητὰς ἐκείνων γεγονέναι μαρτυρίοις πιστωσαμένους τὰς δόξας ταύτας παλαιὰς εἶναι τοῖς αὐτοῦ τοῦ Πλάτωνος γράμμασιν.

A.H. Armstrong's translation and note:

And [it follows] that these statements of ours are not new; they do not belong to the present time, but were made long ago, not explicitly, and what we have said in this discussion has been an interpretation of them, relying on Plato's own writings for evidence that these views are ancient.<sup>3

3</sup> The belief that the true doctrines are present, but often not explicit, in the writings regarded as traditionally authoritative is, for obvious reasons, essential for pagan and Christian traditionalists of the first centuries A.D. (and for Christian traditionalists later): cp. Origen De Principiis I 3.

Hat tip: Eric Thomson.