The first time I heard this word, it seemed to me to have an indefinite article in front of it, and so “his amanuensis” seemed as syntactically coherent as “her a textbook.” And then there was the question of what a manuensis might be – was it something immense, or a manual… or Immanuel?
Others are also occasionally tripped by this word, and not just because of its mixed bag of cups and caps (m n u), balled socks (a e) and snakes (s). Try saying it – it’s like having your tongue do three pushups in rapid succession (it’s like “a man you en sis” if you’re not sure). So it’s no surprise that I recently heard it accidentally said as “a man you essence”.
“A man you essence” – I like that. “This is the essence of a man you could be!” Well, no, not quite so old and spicy. Given that an amanuensis is a sort of secretary – someone who secretes (stores away) the thoughts you secrete (exude), i.e., one who takes dictation, the words or notes that the muse (be it Thalia, Melpomene, Euterpia, or Erato) pours through your mouth flowing through their pen and onto paper – we could say that an amanuensis is a man (or woman) who helps distill your essence. This eau-de-vie is the eau of your vie, and it is you who are the still – and the amanuensis is the flask that catches the spirit. The amanuensis enables the free flow of thought without the creative person needing to bother with transcription, thereby freeing the flow… O come, o come, amanuensis!
Of course, it is a manual task, and that manu is the same one as in manual. And, as it happens, the a originally was a separate word – not the English article, however, but the Latin preposition. A secretary, in Latin, was a servus a manu – a hand servant (“servant to hand”) – and that was shortened to a manu in a way similar to how maître d’ trimmed off a word. And ensis is a Latin suffix of belonging (for instance, my PhD diploma has a seal on it that says Sigillum Universitatis Tuftensis, “seal of the University of Tufts” [i.e., of Tufts University]). So it’s like calling someone who does things by hand a byhander. Except that amanuensis sounds kind of technical and foreign.
And it is typically served in literary contexts, unsurprisingly – it is not ordinary persons like you or I who have amanuenses (note the plural form); it is the exalted authors and composers, the ranks of Henry James and James Joyce and Frederick Delius and such like who do not think onto paper but dream a cloud and exhale it, a numen as is, so it may be condensed into tiny black droplets on white sheets of paper by their hand servants.