Chrysippus' hand

I gave a short paper today to the 1st c. BC philosophy research group on this chapter from Cicero's De Finibus (1.39). It's part of a longer thing I'm working on on the presentation of Epicurean conceptions of pleasure in Fin. 1 and 2 but I'm beginning to think that it's a sufficiently rich little bit of text to warrant some concentrated work. Here it is:

at etiam Athenis, ut e patre audiebam facete et urbane Stoicos irridente, statua est in Ceramico Chrysippi sedentis porrecta manu, quae manus significet illum in hae esse rogatiuncula delectatum: 'Numquidnam manus tua sic affecta, quem ad modum affecta nunc est, desiderat?'– Nihil sane. -- 'At, si voluptas esset bonum, desideraret.'– Ita credo. – 'Non est igitur voluptas bonum.' Hoc ne statuam quidem dicturam pater aiebat, si loqui posset. conclusum est enim contra Cyrenaicos satis acute, nihil ad Epicurum. nam si ea sola voluptas esset, quae quasi titillaret sensus, ut ita dicam, et ad eos cum suavitate afflueret et illaberetur, nec manus esse contenta posset nec ulla pars vacuitate doloris sine iucundo motu voluptatis. sin autem summa voluptas est, ut Epicuro placet, nihil dolere, primum tibi recte, Chrysippe, concessum est nihil desiderare manum, cum ita esset affecta, secundum non recte, si voluptas esset bonum, fuisse desideraturam. idcirco enim non desideraret, quia, quod dolore caret, id in voluptate est.

My father used to mock the Stoics with wit and elegance by telling me how, in the Cerameicus at Athens, there is a statue of Chrysippus sitting with an outstretched hand, that hand symbolizing the delight Chrysippus took in the following little piece of argument: “Does your hand, in its present condition, want anything?” “Not at all.” “But if pleasure were a good, it would be wanting it.” “I suppose so.” “Therefore pleasure is not a good.” My father remarked that not even a statue would produce such an argument, if it could speak. Though the reasoning has some force against a Cyrenaic position, it has none whatsoever against Epicurus. If pleasures were simply the kind of thing which, so to speak, titillated the senses and flooded them with a stream of sweetness, then neither the hand nor any other part of the body could be satisfied with the mere absence of pain and no delightful surge of pleasure. But if, as Epicurus maintains, the highest pleasure is to feel no pain, well then, Chrysippus, the initial concession, that the hand in its present condition wants nothing, was correct; but the subsequent one, that if pleasure were a good the hand would have wanted it, is not. For the reason that it did not want it was that to have no pain is precisely to be in a state of pleasure. (trans. R. Woolf)

I think it's very interesting and the discussion set me thinking in some interesting directions. But I am surprised that I can't find very much written about it. Gosling and Taylor say a little bit in The Greeks on pleasure (though they aren't interested at all in the dialogue's internal dialectic and report this all as what 'Cicero' writes) and there are some pointers in Madvig's notes, but there isn't much else. I wonder if anyone out there knows of something else.

I'm particularly interested in the presentation of Chrysippus here. I think there's enough evidence that he and Zeno liked to use hands and hand gestures to illustrate philosophical points. But what about the argument itself? Torquatus seems to be made out to present a nice Stoic dialectical syllogism, in question-and-answer form. He even refers to the premises in Stoic terms (primum... secundum...) So is this ever discussed in the treatments of Stoic logic (esp. Stoic conditionals)?