Ed Simon at The Millions:
Take the word “understand;” in daily communication we rarely parse it’s implications, but the word itself is a spatial metaphor. Linguist Guy Deutscher explains in The Unfolding of Language: An Evolutionary Tour of Mankind’s Greatest Invention how “understand,” derived from the Middle English understanden, itself from the Anglo-Saxon understandan, and ultimately from the Proto-Germanic understandana. “The verb ‘understand’ itself may be a brittle old skeleton by now,” Deutscher writes, “but its origin is till obvious: under-stand originally must have meant something like ‘step under,’ perhaps rather like the image in the phrase ‘get to the bottom of.’” Such spatial language is common, with Deutscher listing “the metaphors that English speakers use today as synonyms: we talk of grasping the sense, catching the meaning, getting the point, following an explanation, cottoning on to an idea, seeing the difficulty.” The word “comprehend” itself is a metaphor, with an etymology in the Latin word prehendere, which means “to seize.” English has a propensity to those sorts of metaphors, foreign loan words from Anglo-Saxon, Frisian, and Norman; Latin, French, Italian, and Spanish; Abenaki, Wolof, and Urdu, which don’t announce themselves as metaphors precisely because of their foreignness—and yet that rich vein of the figurative runs through everything. Dan Paterson gives two examples in his voluminous study The Poem, explaining how a word as common as “tunnel” is from the “Medieval English tonel, a wide-mouthed net used to trap birds, so its first application to ‘subterranean passage’ will have been metaphorical—and would inevitably have carried the connotation ‘trap’ for a little while.”
more here.