The region belonging to the pure intellect is straitened: the imagination labours to extend its territories, to give it room. She sweeps across the boarders, searching out new lands into which she may guide her plodding brother. The imagination is the light which redeems from the darkness for the eyes of the understanding. Novalis says, 'The imagination is the stuff of the intellect' -affords, that is, the material upon which the intellect works.
George MacDonald (1883). “The Imagination: And Other Essays”