Plato's Sophist [51-52]

In the case of ποίησις, the τέλος is something other, a worldly being over and against Dasein; not so in the case of πρᾶξις.

Now, to what extent is φρόνησις an ἀληθεύειν?

b) Φρόνησις as ἀ-ληθεύειν. ἡδονή and λύπη. Σωφροσύνη.
Φρόνησις as a struggle against Dasein's inherent tendency
to cover itself over. Φρόνησις as non-autonomous ἀληθεύειν
in the service of πρᾶξις.

Insofar as man himself is the object of the ἀληθεύειν of φρόνησις it must be characteristic of man that he is covered up to himself, does not see himself, such that he needs an explicit ἀ-ληθεύειν in order to become transparent to himself. In fact, διαφθείρει καὶ διαστρέφει τὸ ἡδὺ καὶ τὸ λυπηρὸν τὴν ὑπόληψιν (cf. b13f.). "What gives pleasure and what depresses one's disposition can destroy or confuse one's ὑπόληψις." A disposition can cover up man to himself. A person can be concerned with things of minor significance; he can be so wrapped up in himself that he does not genuinely see himself. Therefore he is ever in need of the salvation of φρόνησις. Circumspection regarding himself and insight into himself must again and again be wrested away by man in face of the danger of διαφθείρειν and διαστρέφειν. It is not at all a matter of course that Dasein be disclosed to itself in its proper Being; ἀλήθεια, even here, must be wrested out. And in this way Aristotle, like Plato, assumes a peculiar etymological relation. σωφροσύνη σῴζει τὴν φρόνησιν (cf. b11f.). "Prudence is what saves φρόνησις," preserves it against the possibility of being covered over. Plato determines σωφροσύνη in a similar manner in the Cratylus: "σωφροσύνη" δὲ σωτηρία... φρονήσεως (411e4f.). But ἡδονή and λύπη threaten only certain modes of ἀληθεύειν. οὐ γὰρ ἅπασαν ὑπόληψιν διαφθείρει οὐδὲ διαστρέφει τὸ ἡδὺ καὶ λυπηρόν [...], ἀλλὰ τὰς περὶ τὸ πρακτόν (Nic. Eth. VI, 5, 1140b13ff.). "For what gives pleasure and what depresses do not destroy or confuse every ὑπόληψις but only the one related to the πρακτόν. " Yet insofar as ἡδονή and λύπη are among the basic determinations of man, he is constantly exposed to the danger of covering himself to himself. Φρόνησις, consequently, cannot at all be taken for granted; on the contrary, it is a task, one that must be seized in a φρόνησις. Φρόνησις thus eminently illustrates the meaning of ά-ληθεύειν, i.e., the uncovering of something concealed. Aristotle emphasizes: τῷ δὲ διεφθαρμένῳ δι' ἡδονὴν ἢ λύπην εὐθὺς οὐ φαίνεται ἀρχή (b17f.). "Dasein Can be corrupted by ἡδονή and λύπη." If one of these dominates a man, the result is that οὐ φαίνεται ἡ ἀρχή. The correct οὗ ἕνεκα no longer shows itself; it is thus concealed and must be uncovered through λόγος. In this way, therefore, φρόνησις, as soon as it is achieved, is involved in a constant struggle against a tendency to cover over residing at the heart of Dasein.

Martin Heidegger (GA 19) Plato's Sophist