τὸ δ' ἐξαίφνης τὸ ἐν ἀναισθήτῳ χρόνῳ διὰ μικρότητα ἐκστάν → suddenly refers to what has departed from its former condition in a time imperceptible because of its smallness
in the usual way: P. and V. εἰωθότως, P. συνήθως.
generally, for the most part: P. ὡς ἐπὶ πολύ.