Laudator Temporis Acti

Simonides, fragment 19 (tr. M.L. West):

  This finest thing the Chian said:
'As is the breed of leaves, e'en so is that of man.'
  Few mortals who have had that in their ears
have taken it to heart, for everyone relies
  on hope; it's planted in a young man's breast.

  ἓν δὲ τὸ κάλλιστον Χῖος ἔειπεν ἀνήρ·
"οἵη περ φύλλων γενεή, τοίη δὲ καὶ ἀνδρῶν"·
  παῦροί μιν θνητῶν οὔασι δεξάμενοι
στέρνοις ἐγκατέθεντο· πάρεστι γὰρ ἐλπὶς ἑκάστωι
  ἀνδρῶν, ἥ τε νέων στήθεσιν ἐμφύεται.

Simonides, fragment 20, lines 5-12 (tr. M.L. West):

A mortal, while he has the lovely bloom of youth,
  has many empty-headed, vain ideas.
He has no expectation of old age or death,
  and while in health, has no thought of disease.
They're fools who have that attitude, and do not know
  the time allowed to us for youth and life
is short. Take note of this, and till your days are done
  don't waver, treat your soul to all that's nice.

θνητῶν δ' ὄφρά τις ἄνθος ἔχει πολυήρατον ἥβης,
  κοῦφον ἔχων θυμὸν πόλλ' ἀτέλεστα νοεῖ·
οὔτε γὰρ ἐλπίδ' ἔχει γηρασέμεν οὔτε θανεῖσθαι,
  οὐδ', ὑγιὴς ὅταν ἦι, φροντίδ' ἔχει καμάτου.
νήπιοι, οἷς ταύτηι κεῖται νόος, οὐδὲ ἴσασιν
  ὡς χρόνος ἔσθ' ἥβης καὶ βιότοι' ὀλίγος
θνητοῖς. ἀλλὰ σὺ ταῦτα μαθὼν βιότου ποτὶ τέρμα
  ψυχῆι τῶν ἀγαθῶν τλῆθι χαριζόμενος.