In αἴσθησις, as it occurs in geometry, I see the triangle at one stroke as the most original element, which cannot itself be resolved again into more elementary figures.
Just as in geometry an αἰσθάνεσθαι provides the ἔσχατον, so also in φρόνησις. It is essential thus that in this αἴσθησις something shows itself straightforwardly, purely and simply. Aristotle emphasizes that with this sort of coming to an end of the consideration, the deliberation στήσεται (a29), "stands still"; it goes no further. This αἴσθησις is here in φρόνησις, as in geometry, a stopping in which it is only and essentially a matter of putting oneself in opposition to something, allowing it to be encountered simply and purely. Such νοεῖν is a matter of a simple presentifying of something, so that it speaks purely out of itself and no longer requires discourse or a demonstration on our part. Here it can still be said: φαίνεται, the things show themselves in this way. The only possibility here is to look on and, in looking, to grasp.
Aristotle describes this nexus still more extensively in Nicomachean Ethics III, 5, 1112b11ff.4 There he returns to the content of geometry, to the διάγραμμα. Aristotle proceeds from deliberation: one does not deliberate about the τέλος, but instead the τέλος is the object of a decision. The object of the deliberation is συμφέρον πρὸς τὸ τέλος, that which is pertinent to the correct bringing to an end of what has been decided. βουλευόμεθα δ᾽ οὐ περὶ τῶν τελῶν ἀλλὰ περὶ τῶν πρὸς τὰ τέλη. οὔτε γὰρ ἰατρὸς βουλεύεται εἰ ὑγιάσει, οὔτε ῥήτωρ εἰ πείσει, οὔτε πολιτικὸς εἰ εὐνομίαν ποιήσει, οὐδὲ τῶν λοιπῶν οὐδεὶς περὶ τοῦ τέλους (b11ff.). A doctor does not deliberate about whether he is going to heal; on the contrary, that belongs to the meaning of his existence itself, because as a doctor he has already resolved in favor of healing. Just as little does the orator deliberate about whether he should convince; for that lies in the very sense of his existence. ἀλλὰ θέμενοι τὸ τέλος τὸ πῶς καὶ διὰ τίνων ἔσται σκοποῦσι (b15f.). The τέλος is thus a τέλος τεθέν; the end is posited and held fast. In their deliberating the doctor or orator do not have this in view but instead the πῶς καὶ διὰ τίνων, the how and the ways and means. And they look around, in each case within the concrete situation of their acting, until ἕως ἂν ἔλθωσιν ἐπὶ τὸ πρῶτον αἴτιον, ὃ ἐν τῇ εὑρέσει ἔσχατόν ἐστιν (b18ff.), until their consideration touches the first αἴτιον whence they can intervene, that which, in the uncovering of the whole state of affairs, is the outermost of the deliberation. ὁ γὰρ βουλευόμενος ἔοικε ζητεῖν καὶ ἀναλύειν τὸν εἰρημένον τρόπον ὥσπερ διάγραμμα . . ., καὶ τὸ ἔσχατον ἐν τῇ ἀναλύσει πρῶτον εἶναι ἐν τῇ γενέσει (b20ff.). The ἔσχατον of the ἀνάλυσις is what is first for ποίησις, i.e., where the ποίησις, the genuine becoming, begins. This passage in the Nicomachean Ethics is thus of importance because Aristotle does not speak there of ποίησις but explicitly of πρᾶξις in the strict sense.5
4. Cf. in addition 1113a2ff.
5. Versus the corresponding analyses of ποίησις in Met. VII, 7, 1032bff. Cf. p. 108ff.