Degree of Utility
This phrase was first made current by Jevons in his Theory of Political Economy, 1871. Its precise significance will be best elucidated by an analogy. ‘Degree of utility’ stands in the same relation to ‘total utility’ as ‘velocity’ to ‘space traversed’. Suppose we have a body projected vertically upwards from rest, at a given speed. We may inquire first at what height the body will be found at any moment after its projection, and second at what rate it will be moving at any point of its course, and clearly the rate of its movement is the rate at which its height is increasing (whether positively as it rises, or negatively as it falls). This rate may be measured in feet per second, or in miles per hour, or in any other suitable unit, but in any case it varies from point to point and does not continue the same during any period, however short.