Final answer:
In 'The Pilgrim's Progress,' Christian and Hopeful are clothed in robes of righteousness as they enter the Celestial City, symbolizing their spiritual transformation and salvation.
Step-by-step explanation:
In John Bunyan's classic work The Pilgrim's Progress, Christian and Hopeful are clothed in robes of righteousness when they enter the Celestial City. This imagery is symbolic of Christian redemption and salvation, reflecting the transformation of the pilgrims from their sinful beginnings to their glorified state in heaven. These robes represent the purity and righteousness that is granted to them, not through their own deeds, but through their faith and by the grace of God.