This section is from the book "The Law Of Contracts", by William Herbert Page. Also available from Amazon: Commercial Contracts: A Practical Guide to Deals, Contracts, Agreements and Promises.
If we take the classic common-law classification of contracts, and strike out the contracts which are recognized at modern law as genuine contracts, we have left two classes. These are (1) the contracts of record, and (2) the second class of the so-called implied contracts, consisting of rights enforceable at common law by the action of assumpsit, and hence classed as contract; but not originating in the voluntary agreement of the parties, and hence excluded from the modern classification of contract. There is a strong tendency at modern law to separate these rights entirely from genuine contract and to class them as quasi-contract or as constructive contracts. The historical classification of the common law has resisted this tendency to a great extent. Out of deference to the traditional classification, therefore, constructive contracts or quasi-contracts are discussed hereafter, and their present relation to contract is here outlined.1