In Ouidah, a small town and former slave port in the West African country of Benin, the annual voodoo festival gathers visitors from far and wide. It brings together priests and dignitaries, rich and poor, locals and visitors from as far afield as the Caribbean and France. The festival commemorates the estimated 60 million people who lost their homelands and their freedom during the African slave trade. Slaves were transported from the town on the Atlantic from Nigeria, Togo, Ghana and other parts of West Africa. The traditional African religion, which spread to the Americas with the slave trade, combines elements including philosophy and medicine. The central belief of voodoo is that everything is spirit, including humans. Voodoo is closely related to other belief systems and religions I have seen across Africa, especially back home in Nigeria. The annual Ouidah gathering has been a national holiday in Benin for more than 20 years. The gathering includes traditional dance and animal sacrifices at shrines, with some devotees entering trance states. The peak of the festival is in the last two days. Devotees offer dances to the spirits, often with bodies decorated with powder and palm oil. Some find the initiation ceremonies of voodoo, the animal sacrifices, the bloodletting and the use of fetishes unsettling. Although many voodoo practices have been modified over the years, I have heard people, especially those who follow Christianity and Islam, voice their doubts. Whatever your opinion of voodoo, it's hard to ignore the energy and devotion of its followers at a gathering like this. The Ouidah festival looks set to remain a regular fixture in Benin's religious and cultural calendar.