Note 7:1 — INTRODUCTION.[vii:1]
Andrew P. (Andrew Preston) Peabody translation
The reference here is, undoubtedly, to an hexameter verse from some unknown poet, quoted by Sextus Empiricus in the third century:—
Ὀψὲ θεῶν ἀλέουσι μύλοι, ἀλέουσι δὲ λεπτά. “The mills of the gods grind late, but they grind fine.”