Digging Up the History of Delve

We must dig deep into the English language's past to find the origins of delve. The verb traces to the early Old English word delfan and is related to the Old High German word telban, meaning "to dig." For centuries, there was only delving—no digging—because dig didn't exist until much later; it appears in early Middle English. Is the phrase "dig and delve" (as in the line "eleven, twelve, dig and delve," from the nursery rhyme that begins "one, two, buckle my shoe") redundant? Not necessarily. According to the Oxford English Dictionary, in some local uses, dig was the term for working with a mattock (a tool similar to an adze or a pick), while delve was reserved for work done using a spade.