There may be a certain amount of convenience in having a timepiece in every room of a house; still the convenience of the first, that is, the importance of having one, is probably greater than that of all the rest put together. So, a person who has one house may wish to have a second, but still the want of the second is not equal to that of the first.
William F. Lloyd, “A Lecture on the Notion of Value as Distinguished Not Only From Utility, but also from Value in Exchange” (University of Oxford, 1833). This lecture is an early explication of the principle of diminishing marginal utility, a central concept in economics. The formal statements of the notion were published by other economists from 1870 on.