In April-May 1802 was Coleridge revolving, among other things, a Miltonic something. In late April he jotted in his notebook an idea for a new poem: ‘Milton, a Monody in the metres of Samson's Choruses—only with more rhymes/—poetical influences—political—moral—Dr Johnson/’ [Notebooks 1:1155]. This particular poem never got itself written, but a few days later a grumpy, or perhaps wryly scatological, Coleridge jotted down the following:
Unintelligible? As well as call a Fart unintelligible / it tells you at once what it is—it is nonsense—enigmata quia non Sphinx sed Sphincter anus. [Notebooks 1:1184]Kathleen Coburn translates the Latin (‘riddles not from the Sphinx but the sphincter’ is her version, omitting the entry's terminal word) but doesn't realise it's a quotation, and so speculates about his point: ‘abuse need not be intelligible in itself; it requires only to be recognized as abuse.’
In fact the Latin is taken from Milton's sixth Prolusion ¶ 3, where an individual is ridiculed for uttering ‘aenigmata quaedam nolens effutiat sua non Sphinx sed sphincter anus, quae medicis interpretanda non Oedipo’, ‘riddles merely farted out, issuing not from the Sphinx but the anal sphincter, more fitting for doctors to interpret than Oedipus’. This wasn't exactly typical Miltonic Latin, although, as Anna Beer points out, neither was it wholly uncharacterstic. Beer notes that in Milton’s day ‘performing in Latin was a cornerstone of the Cambridge experience’ and that whilst most of Milton’s surviving Latin speeches are ‘dull’ (for instance: ‘Prolusion 1’ on the question of whether day or night is better, or ‘Prolusion 2’ on the music of the spheres) Prolusion 6 is considerably saucier.
In May 1628 [Milton] ‘was approached to be “Father” during a “salting”, a traditional feast of misrule, which focused on the initiation of young men into the college.’ Initiates might find themselves having to drink salted ale, but in addition to literal salt, there was metaphorical salt: ‘the occasion was full of sales, salty, sexual wit, redolent of licenced indecorum … Milton’s role in the Cambridge salting was as master of ceremonies. He was “Father” for the day, elevated above his “brothers” in this licensed folly.’ He started things off with a speech full of rudery (in Latin of course). Beer notes how tempting was the ‘opportunity for humour, particularly for a chaste figure like the nineteen-year-old John’. [Anna Beer, Milton: Poet, Pamphleteer and Patriot (London: Bloomsbury 2011), 75]. The Latin was first published in Joannis Miltonii Angli, Epistolarum familiarium liber unus quibus accesserunt, ejusdem, jam olim in collegio adolescentis, prolusiones quaedam Oratoriae (1674).
It's quite cool to be able to track this allusion down, actually, not least because it suggests Coleridge wasn't necessarily jotting something down out of pique because he had been called ‘unintelligible’ (and indeed it's a little hard to make sense of the entry on those terms). Rather he's using the apparent dignity of Miltonic Latin to suggest that everything means, even if it only ‘means’ on the level of performing itself as non-meaning. And given that whatever prompted this notebook entry put STC in mind of this particular Miltonic prolusion, conceivably he was thinking about laughter as such: a sort of utterance that is, on the level of semantic content, merely unintelligble noises, but which nonetheless signifies, richly.