Obligation is a legal bond or tie whereby constraint is laid upon a person or group of persons to act or forbear on behalf of another person or group. Since there can be no contract without obligation, every element essential to the creation of an obligation is essential to the creation of a contract.
From the very nature of things, two persons are necessary. There may be more than two, but there cannot be less. A man cannot be under a legal obligation to himself, or even to himself in conjunction with others. In an English case, where a man had borrowed money from a fund in which he and others were jointly interested, and covenanted to repay the money to the joint account, it was held that he could not be sued upon his covenant. "The covenant, to my mind, is senseless," said Pollock, C. B. "I do not know what is meant, in point of law, by a man paying himself."15 And in a Massachusetts case it was said that "it is a first principle that, in whatever different capacities a person may act, he never can contract with himself, nor maintain an action against himself. He can in no form be both obligor and obligee."16