Origins
The verb 'explicate' is the etymological mirror image of 'complicate.' Where 'complicate' folds things together into a tangle, 'explicate' unfolds them, laying each element out for inspection. Latin 'explicāre' combined 'ex-' (out) with 'plicāre' (to fold), producing 'to unfold, to unroll, to spread out.' The word carried both physical and intellectual senses in Latin: unrolling a scroll to read it, and unraveling a difficult argument to understand it.
The physical sense was primary in early Latin. Roman books were scrolls ('volumina,' from 'volvere,' to roll — whence 'volume'), and reading literally required unfolding or unrolling. To 'explicate' a text was to unroll the scroll and expose its contents. This concrete image of physical unfolding became the standard metaphor for intellectual clarification — making the hidden visible, the obscure clear.
English borrowed 'explicate' directly from Latin in the 1530s, following the Renaissance appetite for classical vocabulary. The word has always occupied a higher register than its popular cousin 'explain' — which also derives from 'explicāre' but arrived much earlier through Old French 'esplanier' (to flatten out, make plain), where the folding metaphor was transformed into a flattening metaphor. Both 'explicate' and 'explain' mean 'to make clear,' but 'explicate' implies detailed, systematic analysis while 'explain' suggests a more general clarification.
Latin Roots
The adjective 'explicit' (from Latin 'explicitus,' past participle used as an adjective) entered English in the early seventeenth century. Something explicit has been fully unfolded — nothing is hidden, everything is stated directly. Its antonym 'implicit' (from 'implicitus,' folded in) describes what remains folded inside, unstated but present. The explicit/implicit pair is one of the most useful conceptual tools in English, and its power derives from the folding metaphor: meaning can be either unfolded for all to see or folded in for the perceptive to discover.
Medieval manuscripts often bore the Latin word 'EXPLICIT' at the end of a work, meaning 'it is unfolded' or 'it is completed' — the text has been fully unrolled and read. This scribal convention is the direct ancestor of modern usage, where 'explicit' means openly stated. The medieval scribe's 'EXPLICIT' was both a physical description (the scroll is unrolled) and a conceptual one (the text is complete).
In literary criticism, 'explication' (close reading and analysis of a text, especially poetry) became a formal methodology in the twentieth century through the New Criticism movement. 'Explication de texte' — borrowed from French pedagogical tradition — treats a poem or passage as something folded that requires careful, systematic unfolding to reveal its layers of meaning. The etymological metaphor could hardly be more apt: a dense poem is indeed like a folded document, its meanings layered and compressed, requiring patient unfurling.