Is this word "manuducant" a typo or an obscure word?

Question

I have the following sentence from Euler's De Serie Lambertina (I've already asked half a dozen questions about this paper), and one of the words manuducant (manvdvcant), shown in the snippet below, doesn't seem to be a word as written.

It seems like the sentence reads

Operationes analiticas exponere, quae ad cognitionem verae summae seriei Lambertinae manuducant.

Which translates to

Set forth the analytical operations, which [manuducant] to the understanding of the actual sum of the Lambert series.

As I see it, the word relates to duco, so it would be something like "which leads to the understanding...", but I'm unsure of the intention here, maybe "manu ducant"?

Answer 1

Manuductio (verb: manuduco) is a late Latin word that literally means, "leading by the hand." See, for instance, "Mind Forming and Manuductio in Aquinas" (pay-wall protected), which discusses the word in the works of Thomas Aquinas.

The Dictionnaire latin-français des auteurs du Moyen-Age gives as its earliest citation a work by Thomas Gallus (early 13th c.)--though, as cnread helpfully points out, the related word manuductor does have earlier attestations. Thomas Aquinas uses manuductio and manuduco quite frequently, as you can verify in the Index Thomisticus.

Based on the fact that the earliest citations of this word in Latin come from commentaries on an extremely popular work translated from Greek, Pseudo-Dionysus's De Divinis Nominibus, it is likely that it came into Latin as a literal translation of a slightly more common Greek term: χειραγωγία, literally "hand-leading." At this time, many of the Latin translations of Greek works (such as those of William of Moerbeke) were scrupulously literal.

Manuductio seems to become a common word in Scholastic and Later Latin (such as the work you cite by Euler). The intended sense is a little more specific than just "introduction": it generally refers to "leading someone to an understanding of something through specific examples."