"But the facts of Nature are to be discovered only by observation and experiment." True. But how does the man of science come to think of his experiments? Does observation reach to the non-present, the possible, the yet unconceived? Even if it showed you the experiments which ought to be made, will observation reveal to you the experiments which might be made? And who can tell of which kind is the one that carries in its bosom the secret of the law you seek? We yield you your facts. The laws we claim for the prophetic imagination. "He hath set the world in man's heart," not in his understanding. And the heart must open the door to the understanding. It is the far-seeing imagination which beholds what might be a form of things, and says to the intellect: "Try whether that may not be the form of these things;" which beholds or invents a harmonious relation of parts and operations, and sends the intellect to find out whether that be not the harmonious relation of them--that is, the law of the phenomenon it contemplates. Nay, the poetic relations themselves in the phenomenon may suggest to the imagination the law that rules its scientific life. Yea, more than this: we dare to claim for the true, childlike, humble imagination, such an inward oneness with the laws of the universe that it possesses in itself an insight into the very nature of things.
George MacDonald, The Imagination: Its Function and Its Culture