Where does “literally” come from?

I need to work through this chain carefully, but I notice there are significant problems with it that make it impossible to write an accurate etymology sentence. The chain as presented doesn't make coherent sense: - "literally" comes from "literal" + "-ly" (the adverbial suffix) - "literal" comes from Middle English and Old English "-līċ" (an adjective suffix) - But the chain then jumps to Latin -alis, Ancient Greek διφθέρα (diphthera, meaning "leather"), and PIE roots that don't connect to the meaning of "literal" This chain appears corrupted or mixed with a different word's etymology. The actual etymology of "literal" should trace through Latin *litteralis* (from *littera*, letter) rather than through διφθέρα (leather). **I cannot write an accurate one-sentence etymology using this chain as given, because

literally (English): word for word; not figuratively; not as an idiom...