In Indigenous worldviews -- where humanity, nature, and the spiritual realm are closely connected -- the night sky provides spiritual and navigational guidance, timekeeping, weather prediction, and stories and legends that tell us how to live a proper life. Cultural astronomy, also referred to as archaeoastronomy or ethnoastronomy, explores the distinctive ways that astronomy is culturally embedded in the practices and traditions of various peoples.In Part 4, Babatunde Lawal gives a talk entitled "A Big Calabash with Two Halves: The Yoruba Vision of the Cosmos." Afterwards, Douglas Herman, Senior Geographer of the National Museum of the American Indian, moderates a Question and Answer segment featuring Babatunde Lawal, John MacDonald, and Michael Wassegijig Price.Babatunde Lawal is a professor Art History at Virginia Commonwealth University, Richmond, Virginia. He specializes in African and African Diaspora art with a personal research focus on the ancient and contemporary arts of Nigeria, particularly the visual culture of the Yoruba and its influences in the Americas. His publications on Yoruba art examine its ontological, social, cultural, religious and aesthetic implications as well as the dynamics of change. Much of his data derives from formal and iconographic analyses reinforced with field interviews and the Odù Ifá, a collection of origin myths, astronomical speculations, philosophical commentaries and remedies handed down from the past and often referenced by Yoruba diviners to help clients in times of crisis. Babatunde Lawal's presentation at the symposium will focus on the Yoruba vision of the cosmos as "a big calabash with two halves." The top represents the male Sky, and the bottom, female Earth. The calabash is thought to be sustained by a constellation of metaphysical and physical phenomena (àse) on which depends the future of humankind. So it is that cultural astronomy looms large in Yoruba culture and art, being used for a variety of purposes such as social control, measuring time, determining direction, coping with the vicissitudes of the existential process and, most importantly, reinforcing their belief in life after death.The symposium was webcast on October 20, 2012 from the Rasmuson Theater in the National Museum of the American Indian on the National Mall in Washington, DC.