The trickle-down effect is a model of product adoption in marketing that affects many consumer goods and services. It states that fashion flows vertically from the upper classes to the lower classes within society, each social class influenced by a higher social class. Two conflicting principles drive this diffusion dynamic. Lesser social groups seek to establish new status claims by adopting the fashions of higher social groups in imitation, whilst higher social groups respond by adopting new fashions to differentiate themselves. This provokes an endless cycle of change, driving fashion forward in a continual process of innovation. Due to this dynamic, initially, a product may be so expensive that only the wealthy can afford it. Over time, however, the price will fall until it is inexpensive enough for the general public to purchase. History and evolution of the term The trickle down theory has been modified greatly from the Veblen-Jhering model, produced in the end of the 19th century, to date. However, it provides an overall theory of how novelty is first introduced then disseminated throughout society. Von Jhering The German jurist Rudolf von Jhering is probably the first author who developed a full theory of cultural diffusion from the upper classes to the lower classes, applied to fashion, in his book Der Zweck im Recht (second volume, 1883). The French sociologist Émile Durkheim summarizes Von Jhering's theory: "[According to this author, fashion] is the result of the need for superior classes to distinguish themselves on the outside from the inferior classes. Because on one side the latter constantly tend to imitate the former, fashion spreads in society by means of contagion. But, on the other side, because it lost all its value once it is adopted by everybody, it is condemned by its very nature to renew itself continuously". It can be observed that it is not Georg Simmel who invented the trickle-down theory: in his 1904 article this author does not even cite his compatriot, unlike Durkheim seven years earlier. Veblen The theory of conspicuous consumption was introduced by Thorstein Veblen in his book The Theory of the Leisure Class. The oldest theory of distribution, it poses that people spend money on obtaining luxury goods and services to give an indication of their wealth to other members of society. He highlights society's endless quest for novelty maintaining that 'elegance' or elaborateness of dress, and new styles, which are