From 30 April to 4 September 2005, the Museum of Design in Zurich staged the exhibition 'Simply complex' ('einfach Komplex'), an exploration of the dendritic form. The dendritic form is a recurrent and often instructive one in the sciences, which can be observed in many contexts and at different scales, from the delta of liquid methane revealed by the Huygens probe on the surface of Saturn's moon Titan in 2005, to micrographs of neurons in the human brain. It also recurs in the form of the persuasive diagrams which art historians, linguists and philosophers have long used to bring forth a sense of organic unity, order and development from their data. 'Simply complex' displayed case studies of these visual strategies in the sciences, while also showcasing some specially commissioned critical and aesthetic interventions by artists on the theme of the branching form. Here I reflect on the planning process for the exhibition, and present for the first time in English my essay from the accompanying book.