usury — cardinal rules

There are two cardinal rules in the doctrine of usury, which we think must be regarded as the common-place to which all reasoning and adjudication upon the subject should be referred. The first is, that to constitute usury, there must be a loan in contemplation by the parties; and the second, that a contract, which, in its inception, is unaffected by usury, can never be invalidated by any subsequent usurious transaction.