More about arcane
Arcane “known by very few” comes by way of Middle French from Latin arcānus “secret, concealed,” from the verb arcēre “to shut up, keep.” Arcēre (stems arc- and erc-) is also the source of coerce and exercise, and it derives from arca “chest, box,” which is the source of ark. Despite the resemblance, arca is not related to arcus “bow, curve,” the latter of which is the ancestor of arc, arcade, arch, and archer. Thanks to Grimm’s law, Latin c tends to correspond to Old English h, and Latin arcus is therefore a distant relative of arrow (from Old English earh). Arcane was first recorded in English in the 1540s.