Oliver Wendell Holmes, Jr., Wisconsin Michigan Railway Company v…
“ But the other elements are that the promise and the detriment are the conventional inducements each for the other. No matter what the actual motive may have been, by the express or implied terms of the supposed contract, the promise and the consideration must purport to be the motive each for the other, in whole or at least in part. It is not enough that the promise induces the detriment or that the detriment induces the promise, if the other half is wanting. ”
