Haitian ritual drumming uses three drums of graduated size — manman, segon and boula — playing interlocking patterns, with the manman player, the most senior, carrying the lead. Each nanchon has its own rhythms and each lwa its own within them, so the drumming names who is being called. The technically critical element is the kase, the break: a deliberate disruption of the established pattern, executed by the manman drummer and aimed at a particular dancer, which cuts across the rhythm they have entrained to. The kase is understood as the instrument by which possession is precipitated, and a drummer who can place one accurately is a specialist of high standing, known by name well beyond his own district. Drums are consecrated objects with their own ceremonies. This body of knowledge is entirely oral, is acquired from childhood, and is the most technically demanding thing in the religion.