Science does not know its debt to imagination. Goethe did not believe that a great naturalist could exist without this faculty. He was himself conscious of its help, which made him a prophet among the doctors. From this vision he gave brave hints to the zoölogist, the botanist, and the optician. _Poetry._--The primary use of a fact is low: the secondary use, as it is a figure or illustration of my thought, is the real worth. First, the fact; second, its impression, or what I think of it. Hence Nature was called "a kind of adulterated reason." Seas, forests, metals, diamonds, and fossils interest the eye, but 'tis only with some preparatory or predicting charm. Their value to the intellect appears only when I hear their meaning made plain in the spiritual truth they cover. The mind, penetrated with its sentiment or its thought, projects it outward on whatever it beholds. The lover sees reminders of his mistress in every beautiful object; the saint, an argument for devotion in every natural process; and the facility with which Nature lends itself to the thoughts of man, the aptness with which a river, a flower, a bird, fire, day, or night, can express his fortunes, is as if the world were only a disguised man, and, with a change of form, rendered to him all his experience. We cannot utter a sentence in sprightly conversation without a similitude. Note our incessant use of the word _like_,--like fire, like a rock, like thunder, like a bee, "like a year without a spring." Conversation is not permitted without tropes; nothing but great weight in things can afford a quite literal speech. It is ever enlivened by inversion and trope. God himself does not speak prose, but communicates with us by hints, omens, inference, and dark resemblances in objects lying all around us.