Pentecost is the feast Christians use to date their own institution: the account in Acts 2 has the disciples speaking and being understood in a crowd of pilgrims from a dozen regions, and the church counts its beginning from that morning rather than from Easter. The Jewish festival it falls on, Shavuot, is a harvest and covenant feast, and the layering is deliberate. Russian practice fills the church with cut grass and birch branches so the floor is green and the building smells like a field, and the day is popularly called the Trinity. The reading has done a great deal of work in the last century: the Pentecostal movement takes its name from it, and the argument over whether the gifts described continue today or ceased with the apostles is the fault line between roughly half a billion Pentecostals and their cessationist critics.