Special stamp for Swiss Post. Together with three other artists, four sheetlets on stamps on the subject of "Smart City" were realized. Smart City is a collective term for holistic development concepts aimed at making cities more efficient, technologically advanced, greener and more socially inclusive. These concepts include technical, economic and social innovations. The term is also used in city marketing and by large technology groups. Presenting this complexity on 4x4cm was not an easy task right away. After several drafts, I got stuck on the city's signalling. A city or the inhabitants of a city are guided by signals and made aware of certain things. These signs, pictograms and writings in the form of signs help us to give us clues or to pay attention to certain things. They are intended to support and warn residents in everyday life. Without this signaling, there would be chaos in certain situations. With an ironic look at this signage, I show a roundabout signal on the stamp. A butterfly moves easily in the air. His position at that moment is captured by the viewer in the center of the shield. The heart shape of the butterfly is calculus. As a collective, I wish for a clever city that includes and respects the flora and fauna in the urban design. We are a part of nature and are better off with it if we don't stray too far from it. This is my dreamy, optimistic thought of a clever city or of the city developers, architects, economists, investors, etc. of the present and future. The individual works were first painted on an area of 1.2x1.2m and then photographed and reproduced.