This is another reference to The Pilgrim’s Progress. The Celestial City, Bunyan's vision of the New Jerusalem, is the goal towards which Christian strives. As the way is fraught with physical obstacles and moral perils, only the truly righteous are able to approach it. The city stands on top of a hill that reaches above the clouds and is surrounded by a bridgeless moat, the depth of whose waters are determined by the faith of those who enter them. At the summit, worthy souls are admitted through the great gates by a host of angels and welcomed into the paradise of God, where they can enjoy all its sparkling wonders and eat the fruits of the tree of life.
Dimmesdale’s vision of Winthrop’s safe passage into the celestial city amid doubts about the state of his own soul recalls a short story Hawthorne published several years earlier. ‘The Celestial Railroad’ (1843) is a pastiche of The Pilgrim’s Progress in which the arduous road to heaven has been smoothed by all manner of modern conveniences. The moment before realising he will be denied admittance, the narrator watches as two pilgrims who traveled the old-fashioned way are received into their divine destination.