I believe that the Athens were in some ways independently minded and developed a culture of individual freedom where it was considered by many a disgrace to work for someone else. This independence led the lower classes to want to participate in government, and promoted democracy - not today's representative democracy where a member of parliament is supposed to represent the citizens within an electorate, but rather direct democracy, where all the citizens met in assembly each fortnight and made decisions directly on matters put to them by a council, which latter saw to the implementation of their decisions.
Hope this helped :)