ἀπογνωστέον
From LSJ
ἀκμὴ οὐδὲ ἔχει γενέσεως ὑπόστασιν καθ' ἑαυτήν → the culmination has no power of originating by itself
English (LSJ)
A one must give up in despair, ἐλπίδας Ph.1.455, cf. Aristaenet.1.17. 2 one mustreject the view, Plot.4.9.2: c.gen.,Simp.in Ph.610.9.