when beneath the scented hawthorn and the crescent moon it has built itself a palace of emerald light.  This is also one part of nature, one appearance which the glow-worm presents, and that not the least interesting; so poetry is one part of the history of the human mind, though it is neither science nor philosophy.  It cannot be concealed, however, that the progress of knowledge and refinement has a tendency to circumscribe the limits of the imagination, and to clip the wings of poetry.  The province of the imagination is principally visionary, the unknown and undefined:  the understanding restores things to their natural boundaries, and strips them of their fanciful pretensions.  Hence the history of religious and poetical enthusiasm is much the same; and both have received a sensible shock from the progress of experimental philosophy.  It is the undefined and uncommon that gives birth and scope to the imagination; we can only fancy what we do not know.  As in looking into the mazes of a tangled wood we fill them with what shapes we please, with ravenous beasts, with caverns vast, and drear enchantments, so in our ignorance of the world about us, we make gods or devils of the first object we see, and set no bounds to the wilful suggestions of our hopes and fears.

      “And visions, as poetic eyes avow,
      Hang on each leaf and cling to every bough.”

There can never be another Jacob’s dream.  Since that time, the heavens have gone farther off, and grown astronomical.  They have become averse to the imagination, nor will they return to us on the squares of the distances, or on Doctor Chalmers’s Discourses.  Rembrandt’s picture brings the matter nearer to us.—­It is not only the progress of mechanical knowledge, but the necessary advances of civilization that are unfavourable to the spirit of poetry.  We not only stand in less awe of the preternatural world, but we can calculate more surely, and look with more indifference, upon the regular routine of this.  The heroes of the fabulous ages rid the world of monsters and giants.  At present we are less exposed to the vicissitudes of good or evil, to the incursions of wild beasts or “bandit fierce,” or to the unmitigated fury of the elements.  The time has been that “our fell of hair would at a dismal treatise rouse and stir as life were in it.”  But the police spoils all; and we now hardly so much as dream of a midnight murder.  Macbeth is only tolerated in this country for the sake of the music; and in the United States of America, where the philosophical principles of government are carried still farther in theory and practice, we find that the Beggar’s Opera is hooted from the stage.  Society, by degrees, is constructed into a machine that carries us safely and insipidly from one end of life to the other, in a very comfortable prose style.

      “Obscurity her curtain round them drew,
      And siren Sloth a dull quietus sung.”