One of the mysteries of the English language finally explained.
= quantum valebant.
Early 18th century; earliest use found in Ralph Gardiner (b. 1625). From post-classical Latin quantum valebat as much as it was worth from classical Latin quantum which amount + valēbat, 3rd singular imperfect indicative of valēre to be worth.
quantum valebat/ˌkwɒntəm vaˈleɪbat/
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