What is the orgin of the word manure?

First attested in English c.1400, "to cultivate land," also "to hold property," from Anglo-Franc meynoverer, from Old French manouvrer "to work with the hands," from Middle Latin manuoperare, compound from Latin manu operari, from manu, ablative form of manus "hand" + operari "to work, operate" Sense of "work the earth" led to "put dung on the soil" (1599) and to the current noun meaning "dung spread as fertilizer," which is first attested 1549. Until late 18th cent., however, the verb still was used in a figurative sense of "to cultivate the mind, train the mental powers."

"It is ... his own painfull study ... that manures and improves his ministeriall gifts." [Milton, 1641]

Meaning, also, of course;

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