The word "enrichment" has been employed by previous writers to describe this element of quasi contractual obligation. But the term is unsatisfactory in that it connotes an actual increase of the defendant's estate: Such an increase of estate, as will be seen later, must sometimes appear (post, Sec. Sec. 107, 189); but there are many cases, on the other hand, where it is sufficient to show that the defendant has received something desired by him, and the question whether he is thereby enriched in estate is irrelevant (post, Sec. Sec. 107, 118, 119, 125). For example, if A renders services and furnishes material in the erection of a building for B under a supposed contract calling for such services and material, which contract for some reason is invalid, B is under a quasi contractual obligation to pay A the value of such services and material whether or not his property is enhanced in value.1 The broader term "benefit," used in the sense of something desired by the defendant or something advantageous to him, but not necessarily an increase of his estate, seems preferable.