As the disciples watch, Jesus is lifted up and a cloud takes him out of their sight, leaving them standing and gazing up toward heaven until two men in white robes appear and redirect their attention back to earth. The disciples return to Jerusalem and gather in the upper room, where they devote themselves to prayer alongside the women, Mary the mother of Jesus, and his brothers. Peter stands among the gathered believers and addresses the need to replace Judas, whose betrayal and death had left a vacancy among the twelve apostles. Matthias is chosen by lot to take Judas's place, completing the circle of witnesses who will carry forward what they have seen and heard. When the visible disappears, what do we anchor our certainty to?