Laudator Temporis Acti

Aristophanes, Frogs 341-349 (chorus of initiates; tr. Stephen Halliwell):

Iakchos, hail Iakchos,
Our light-bringing star for nocturnal rites!
The meadow blazes with flames of gleaming torches.
Even old men's knees flex in dance.
They shake off all their cares
And the heavy weight of copious years
To join the sacred worship.

Ἴακχ᾽ ὦ Ἴακχε,
νυκτέρου τελετῆς φωσφόρος ἀστήρ.
φλογὶ φέγγεται δὲ λειμών·
γόνυ πάλλεται γερόντων·        345
ἀποσείονται δὲ λύπας
χρονίους τ᾽ ἐτῶν παλαιῶν ἐνιαυτοὺς
ἱερᾶς ὑπὸ τιμᾶς.

Alan H. Sommerstein ad loc.:

343 brilliant star of our nocturnal rites: cf. Soph. Ant. 1146-8 (of Dionysus-Iacchus) "leader of the dance of the stars breathing fire, master of the voices heard by night" (tr. Lloyd-Jones).

345-9 old men's knees leap ... thanks to thy holy worship: likewise in Eur. Ba. 188-190 the power of Dionysus makes old men forget their years (cf. Pl. Laws 666b), and rejuvenation is a recurrent theme of Old Comedy too (e.g. Knights 1321ff, Wasps 1066-7, 1299ff, Peace 349-353, Lys. 667-671, Eccl. 848-850), often taking the form of the recovery of sexual potency by an old man (Dicaeopolis, Demos, Philocleon, Trygaeus, Peisetaerus, Blepyrus).

Plato, Laws 2.666b-c (tr. R.G. Bury):

But when a man has reached the age of forty, he may join in the convivial gatherings and invoke Dionysus, above all other gods, inviting his presence at the rite (which is also the recreation) of the elders, which he bestowed on mankind as a medicine potent against the crabbedness of old age, that thereby we men may renew our youth, and that, through forgetfulness of care, the temper of our souls may lose its hardness and become softer and more ductile, even as iron when it has been forged in the fire.

...τετταράκοντα δὲ ἐπιβαίνοντα ἐτῶν, ἐν τοῖς συσσιτίοις εὐωχηθέντα, καλεῖν τούς τε ἄλλους θεοὺς καὶ δὴ καὶ Διόνυσον παρακαλεῖν εἰς τὴν τῶν πρεσβυτέρων τελετὴν ἅμα καὶ παιδιάν, ἣν τοῖς ἀνθρώποις ἐπίκουρον τῆς τοῦ γήρως αὐστηρότητος ἐδωρήσατο τὸν οἶνον φάρμακον, ὥστε ἀνηβᾶν ἡμᾶς, καὶ δυσθυμίας λήθῃ γίγνεσθαι μαλακώτερον ἐκ σκληροτέρου τὸ τῆς ψυχῆς ἦθος, καθάπερ εἰς πῦρ σίδηρον ἐντεθέντα γιγνόμενον...