Work from René Magritte, surrealism, Belgitude. The origin of surrealism is to be found in Belgium. When you think about it, that’s actually quiet logic.
Belgium is not a real "country". It is rather a surreal patchwork of many different cultures. And languages. We speak Dutch. And French. And German. And English. However, we don’t speak "Belgian". So, although we never really speak the same language, we do have a common language: creativity. It is part of our national attitude, our Belgitude.
Politically, all those cultures in a country the size of a pinhead can create a lot of tension. Obviously. But, for advertising, it’s a truly great gift. It ensures that a Belgian campaign is always an international campaign. Our creative guys and girls are genetically programmed to think in universal ideas. There is no other way. If we can make the French, the Dutch and the Germans laugh, then it is very likely that we will make everybody laugh. Which is why Belgian work tends to please juries. Besides that, Belgium is a small market. Which means that we are used to dealing with small budgets. And small budgets are begging for big ideas.
In summary: little money, no national language and little sense of realism. Life can be cynical, but somehow those are the basic ingredients of why Belgium is a small country with big ideas.