I went to a university performance of Measure for Measure the other night – the first time I’d seen the play in person actually – and noticed anew the violence of a few early lines (1.2.117):
LUCIO
Why, how now, Claudio! whence comes this restraint?
CLAUDIO
From too much liberty, my Lucio. Liberty,
As surfeit, is the father of much fast,
So every scope by the immoderate use
Turns to restraint. Our natures do pursue,
Like rats that ravin down their proper bane,
A thirsty evil; and when we drink, we die.
Some editions alter the opening sense a bit by punctuating Claudio’s first lines differently (From too much liberty, my Lucio, liberty. / As surfeit is the father …) but the rest of the text is secure.
Proper bane would seem to have two tiers of meaning. One is general and follows the metaphor where we are the rats each pursuing our own (=proper) source of harm (=bane). One is particular and connects rats to ratsbane, to what is more literally their own poison. Ratsbane/Ratbane/Rat’s Bane was first attested in 1488 and is used three times elsewhere by Shakespeare.
As best I can tell from the little time I have to give to the question, ratsbane even in the 16th/17th century was typically an arsenic compound (arsenic trioxide), one of whose symptoms was increased thirst. This makes the transferred epithet of thirsty evil both appropriate and all the darker.
I was also curious here about ravin, a variant spelling of (the verb) raven and, past the obvious motivating alliteration, found an interesting suggestion in a recent Notes & Queries article (Sejanus, Measure for Measure, and Rats Bane by Adrien Streete, https://doi.org/10.1093/notesj/gjx218)
This unusual image bears close comparison with Arruntius’ response to Silius’ speech [in Ben Jonson’s Sejanus]:
We that know the evil
Should hunt the palace-rats, or give them bane;
Fright hence these worse than ravens, that devour
The quick, where they but prey upon the dead. (I.426–429)Tiberius’ followers are likened to rats whom those of Arruntius’ faction should poison because they support a ruler who inhibits liberty. Shakespeare reworks this conceit in Claudio’s speech: too much liberty has corrupted his nature which is likened to a rat that greedily devours poison. There may even be a small intertextual in-joke here. Jonson’s noun ‘ravens’, who eat both the living and the dead, are transformed by Shakespeare into the verb ‘ravin’ which, as the OED notes, means ‘the action or practice of seizing and devouring prey or food; predation’, such as a Raven would perform. It is an apt linguistic transformation and shows Shakespeare reworking a striking passage in Jonson’s play in typically imaginative fashion.
Streete also adds a footnote – The image of the rats, thirst, and poison does not appear to be proverbial. The Variorum edition of Measure for Measure quotes an example from 1605, after both plays were written—A New Variorum Edition of Shakespeare: Measure for Measure, ed. Mark Eccles (New York, 1980), 33. I don’t have access to this edition but would be curious to see the example.
Extracts 