Imagination is a condition for truth. Today Lewis is probably most famous as a philosopher and articulate defender of the Christian faith. Some critics have found this odd. Lewis said that imagination actually helps reason. Imagination creates metaphors which in turn produce meaning, and reason cannot function without meaning.
Imagination is necessary for faith.
Thus, to communicate with others even the most reasonable of us must resort to imagination on a daily basis. We also need imagination to develop faith. In The Chronicles of Narnia the children at first cannot get into the land of Narnia because they do not believe in it, and they cannot believe in it because they cannot imagine it. But faith finally prevails because imagination does. The children enter Narnia through a magical wardrobe and have many exciting adventures there as kings and queens of the land.