The intangible heritage is not easy to present in a museum exhibition, and this is perhaps especially so in the case of what the 2003 UNESCO Intangible Heritage Convention terms ‘knowledge and practices concerning nature and the universe’. The Brazilian Federal Museum of Astronomy and Related Sciences (MAST), Rio de Janeiro, initiated an exhibition and educational programme on this theme for International Museums Week in 2004, focusing particularly on four very different cosmologies (i.e. narratives that attempt to explain the origin of the Universe): the Biblical story in Genesis, the contemporary scientific ‘Big Bang’ theory, and the creation stories of two Brazilian indigenous populations: the Tukâno people of the Amazon Region, and the Guarani of southern Brazil and some neighbouring countries. The event called Myths of Origin - man and his comprehension of the Universe and of the planet, on which he lives, consisted of a conceptual, sensory and educational experience whose principal objective was to challenge preconceptions while questioning also the visitors’ perceptions which arise from an educational system where many of these ideas are taught as absolute truths. Following Paulo Freire’s theory of learning and a nonrestrictive understanding of the sciences, we chose to present the four different narratives on an equal basis and invited the visitor to explore these without preconceptions. The underlying objective was to establish a dialogue among these diverse discourses about the cosmos, which we hoped would encourage visitors to take a critical view of the sciences and the way they are interpreted in museums.