The Pilgrim's Progress from this world to that which is to come, delivered under the similitude of a dream

by John Bunyan

This is Christ, who continually, with the oil of his grace, maintains the work already begun in the heart: by the means of which, notwithstanding what the devil can do, the souls of his people prove gracious still. [2 Cor. 12:9] And in that thou sawest that the man stood behind the wall to maintain the fire, that is to teach thee that it is hard for the tempted to see how this work of grace is maintained in the soul.