1911 Encyclopedia Britannica
EARNEST (probably a corruption of the obsolete arles or erles, adapted from Lat. equivalent arrha, due to a confusion with the adjective "earnest," serious, O. Eng. eornust, cognate with Ger. ernst ), the payment of a sum of money by the buyer of goods to the seller on the conclusion of a bargain as a pledge for its due
performance. It is almost similar to the arrha of the Roman law, which may be traced back in the history of legal institutions to a period when the validity of a contract depended not so much upon the real intention of the parties, as upon the due observance of a prescribed ceremony. But earnest was never part payment, which arrha might have been. Apart from its survival as a custom, its chief importance in English law is its recognition by the Statute of Frauds as giving validity to contracts for the sale of goods of a value exceeding Rio (see Sale Of GooDs). It is in that statute clearly distinguished from part payment, consequently any sum, however small, would be sufficient as earnest, being given as a token that the contract is binding and should be expressly stated so by the giver. The giving of earnest, or hand-money, as it is sometimes called, has now fallen into very general disuse.
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Chisholm, Hugh, General Editor. Entry for 'Earnest'. 1911 Encyclopedia Britanica. https://www.studylight.org/encyclopedias/eng/bri/e/earnest.html. 1910.