One of the mysteries of the English language finally explained.
(An action to recover) the reasonable value of goods which have been provided or delivered without a legally enforceable contract stipulating a price.
Of or designating (an action to recover) the reasonable value of goods.
Early 18th century. From post-classical Latin quantum valebant as much as they were worth (apparently not attested in Latin context) from classical Latin quantum which amount + valēbant, 3rd plural imperfect indicative of valēre to be worth.
quantum valebant/ˌkwɒntəm vaˈleɪbant/
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