Is there a proverbial expression it the beginning of Aristophanesʼ <i>Thesmophoriazusae</i>?

Most of Aristophanesʼ commentators, as well as the author of the ancient scholium, believe that Inlawʼs words “Will a swallow ever appear!” in the first line of Aristophanesʼ comedy Women at the Thesmophoria (Thesmophoriazusae) contains a proverbial expression and means: “Will there ever be an end to suffering!” In the 20th century this opinion was denied by Jan van Leeuwen. Van Leeuwen’s doubts are justified: an analysis of references to the swallow in Greek literature shows only that the swallow was strongly associated with the arrival of spring, but the discussed passage from Aristophanes is the first and only case in classical Greek literature when the appearance of a swallow does not just mean the beginning of spring (metonymically), but also relief in general (metaphorically). There is not enough evidence to confirm that such a figurative mention of swallow was proverbial, although this is very likely. If such a proverb was indeed in circulation, then at the beginning of Thesmophoriazusae it is attested for the first time, and this comedy itself is the only one in Aristophanes in which a characterʼs discontent, usual for the prologue, is uttered by means of a figurative paremic expression.