Wealth, in a commercial age, is made up largely of promises. An important part of everyone's substance consists of advantages which others have promised to provide for or to render to him; of demands to have the advantages promised which he may assert not against the world at large but against particular individuals. Thus the individual claims to have performance of advantageous promises secured to him. He claims the satisfaction of expectations created by promises and agreements. If this claim is not secured friction and waste obviously result, and unless some countervailing interest must come into account which would be sacrificed in the process, it would seem that the individual interest in promised advantages should be secured to the full extent of what has been assured to him by the deliberate promise of another. Let us put this in another way. In a former lecture I suggested, as a jural postulate of civilized society, that in such a society men must be able to assume that those with whom they deal in the general intercourse of the society will act in good faith, and as a corollary must be able to assume that those with whom they so deal will carry out their undertakings according to the expectations which the moral sentiment of the community attaches thereto. Hence, in a commercial and industrial society, a claim or want or demand of society that promises be kept and that undertakings be carried out in good faith, a social interest in the stability of promises as a social and economic institution, becomes of the first importance. This social interest in the security of transactions, as one might call it, requires that we secure the individual interest of the promisee, that is, his claim or demand to be assured in the expectation created, which has become part of his substance. In civil-law countries the interest of the promisee, and thus the social interest in the security of transactions, is well secured. The traditional requirement of a _causa ciuilis_, a civil, i.e., legal, reason for enforcing a pact, gave way before natural-law ideas in the eighteenth century. Pothier gave over the contract categories of the Roman law as being "very remote from simplicity." Then came the rise of the will theory of legal transactions in the nineteenth century. French law made intention of gratuitously benefiting another a _causa_. The Austrian code of 1811 presumed a _causa_, requiring a promisor to prove there was none. And this means that he must prove the promise was not a legal transaction--that there was no intention to enter into a binding undertaking. In the result, abstract promises, as the civilian calls them, came to be enforced equally with those which came under some formal Roman category and with those having a substantial presupposition. Modern Continental law, apart from certain requirements of proof, resting on the same policy as our Statute of Frauds, asks only, Did the promisor intend to create a binding duty?