What are the children of men, but as leaves that drop at the wind's breath? 

or

Even as are the generations of leaves, such are those also of men. As for the leaves, the wind scattereth some upon the earth, but the forest, as it bourgeons, putteth forth others when the season of spring is come; even so of men one generation springeth up and another passeth away.

  –Homer in the Iliad, VI, 147. The first translation seems to be by Maxwell Staniforth, as he translated Marcus Aurelius's Meditations, which were written in Greek. The second one is from Oxford University Press's translation of the Iliad by A.T. Murray (1920).

οἵη περ φύλλων γενεὴ τοίη δὲ καὶ ἀνδρῶν.
φύλλα τὰ μέν τ᾽ ἄνεμος χαμάδις χέει, ἄλλα δέ θ᾽ ὕλη
τηλεθόωσα φύει, ἔαρος δ᾽ ἐπιγίγνεται ὥρη:
ὣς ἀνδρῶν γενεὴ ἣ μὲν φύει ἣ δ᾽ ἀπολήγει.