Book excerpt: Yolngu art as a communication system encoding meaning as form; relation of art to the systems of clan organisation and restricted (secret) knowledge; contact history and social contexts of art production; iconography of clan paintings; response to the art market; social organisation rights to land and law; marriage and kinship; rights to paintings; knowledge system - structure, inclusiveness, power, secrecy; role of paintings in ceremonies - burial rituals; range of meanings associated with paintings - examples used in ceremonies associated with the Wawilak Sisters and ancestral shark images; graphic components of painting - figurative and geometric, clan designs; chronological change - the Donald Thomson Collection, past and contemporary categories of painting, commercial art; iconographic analysis of Manggalili clan paintings; relation of events in painting to Yolngu cosmology - creative powers , life and death, male and female dualities.