648 (my own, slightly tendentious, translation):
What good will studying poetry do to help me earn a living?
τί δέ μ' ὠφελήσουσ᾿ οἱ ῥυθμοὶ πρὸς τἄλφιτα;
Jeffrey Henderson's more literal translation:
But how will these rhythms help me get my daily bread?
are barley-groats, but metaphorically they are also (Liddell-Scott-Jones, s.v. ἄλφιτον
, sense III) "one's daily bread, 'bread and cheese'." Liddell-Scott-Jones cite "AR.Pl.
106, etc." for this meaning. A somewhat more complete list, for Aristophanes, would be "AR.Pl.
106, 176, 648, Pax