The Zeitgeist, a word of German origin which literally means the spirit of the time, refers to a set of attitudes, beliefs and ideas that, at one point in time, are accepted uncritically because they appear to be shared by almost everybody. The best way to convince oneself that well-accepted ideas are in fact a product of their time is to look back at past centuries. Two examples from eighteenth-century England may illustrate this point. (i) At that time it was held as self-evident that in order to become an English “citizen” a foreigner had to embrace the Anglican faith. (ii) The fact that trading slaves, provided they were not Christian, was considered a legitimate business for decent Christian merchants is attested by many documents from religious pamphlets to court rulings. Once we have accepted the notion that most of our beliefs are shaped by the society in which we live, we would like to understand how these views, beliefs and convictions are formed. In fact, this question has far reaching consequences in various fields, from marketing to political campaigns to speculation frenzies. In recent times the issue of consensus formation has attracted the attention of econophysicists and several models have been proposed, e.g. Behera and Schweitzer (2003), Quentin and Bouchaud (2005), Stauffer (2003). One of the main difficulties in the study of consensus formation is that we do not know how to distinguish between the action of small and big players. What we mean by these expressions can best be explained through an analogy with stock markets.