But while retrogression is difficult, a fresh advance in conspicuous expenditure is relatively easy; indeed, it takes place almost as a matter of course. In the rare cases where it occurs, a failure to increase one's visible consumption when the means for an increase are at hand is felt in popular apprehension to call for explanation, and unworthy motives of miserliness are imputed to those who fall short in this respect. A prompt response to the stimulus, on the other hand, is accepted as the normal effect. This suggests that the standard of expenditure which commonly guides our efforts is not the average, ordinary expenditure already achieved; it is an ideal of consumption that lies just beyond our reach, or to reach which requires some strain. The motive is emulation--the stimulus of an invidious comparison which prompts us to outdo those with whom we are in the habit of classing ourselves. Substantially the same proposition is expressed in the commonplace remark that each class envies and emulates the class next above it in the social scale, while it rarely compares itself with those below or with those who are considerably in advance. That is to say, in other words, our standard of decency in expenditure, as in other ends of emulation, is set by the usage of those next above us in reputability; until, in this way, especially in any community where class distinctions are somewhat vague, all canons of reputability and decency, and all standards of consumption, are traced back by insensible gradations to the usages and habits of thought of the highest social and pecuniary class--the wealthy leisure class.