something, and the law annexes to the promise or covenant an obligation to do, or refrain from doing, according to the terms of the promise or covenant. But a purely equitable obligation cannot be made in that way. I say “a purely equitable obligation,” because an obligation is frequently annexed to a promise or covenant both by law and by equity, i. e., the law annexes a legal obligation, and equity annexes an equitable obligation. But equity cannot annex an obligation to a promise or covenant to which the law refuses to annex any obligation.[1] In a word, there is properly no such thing as an equitable promise or covenant, and no such thing as an equitable contract. The reason, therefore, why a contract cannot result in creating a purely equitable obligation is, that a contract always results in creating a legal obligation.
How, then, are purely equitable obligations created? For the most part, either by the acts of third persons or by equity alone. But how can one person impose an obligation upon another. By giving property to the latter on the terms of his assuming an obligation in respect to it. At law there are only two means by which the object of the donor could be at all accomplished, consistently with the entire ownership of the property passing to the donee, namely: first, by imposing a real obligation upon the property; secondly, by subjecting the title of the donee to a condition subsequent. The first of these the law does not permit; the second is entirely inadequate. Equity, however, can secure most of the objects of the donor, and yet avoid the mischiefs of real obligations, by imposing upon the donee (and upon all persons to whom the property shall afterwards come without value or with notice) a personal obligation with respect to the property; and accordingly this is what equity does. It is in this way that all trusts are created, and all equitable charges made (i. e., equitable hypothecations or liens created) by testators in their wills. In this way, also, most trusts are created by acts inter vivos, except in those cases in which the trustee incurs a legal as well as an equitable obligation. In short, as property is the subject of every equitable obligation, so the owner of property is the only person whose act or acts can be the means of creating an obligation in respect to that property. Moreover, the owner of property can
