But the imagination has a deeper use than merely to give poets a power of expression.  It is the everlasting preserver of the world from blank materialism.  It forever puts matter in the wrong, and compels it to show its title to existence.  Wordsworth tells us that in his youth he was sometimes obliged to touch the walls to find if they were visionary or no, and such experiences are not uncommon with persons who converse much with their own thoughts.  Dr. Johnson said that to kick one’s foot against a stone was a sufficient confutation of Berkeley, and poor old Pyrrho has passed into a proverb because, denying the objectivity of matter, he was run over by a cart and killed.  But all that he affirmed was that to the soul the cart was no more real than its own imaginative reproduction of it, and perhaps the shade of the philosopher ran up to the first of his deriders who crossed the Styx with a triumphant “I told you so!  The cart did not run over me, for here I am without a bone broken.”

And, in another sense also, do those poets who deal with human character, as all the greater do, continually suggest to us the purely phantasmal nature of life except as it is related to the world of ideas.  For are not their personages more real than most of those in history?  Is not Lear more authentic and permanent than Lord Raglan?  Their realm is a purely spiritual one in which space and time and costume are nothing.  What matters it that Shakespeare puts a seaport in Bohemia, and knew less geography than Tommy who goes to the district school?  He understood eternal boundaries, such as are laid down on no chart, and are not defined by such transitory affairs as mountain chains, rivers, and seas.

No great movement of the human mind takes place without the concurrent beat of those two wings, the imagination and the understanding.  It is by the understanding that we are enabled to make the most of this world, and to use the collected material of experience in its condensed form of practical wisdom; and it is the imagination which forever beckons toward that other world which is always future, and makes us discontented with this.  The one rests upon experience; the other leans forward and listens after the inexperienced, and shapes the features of that future with which it is forever in travail.  The imagination might be defined as the common sense of the invisible world, as the understanding is of the visible; and as those are the finest individual characters in which the two moderate and rectify each other, so those are the finest eras where the same may be said of society.  In the voyage of life, not only do we depend on the needle, true to its earthly instincts, but upon observation of the fixed stars, those beacons lighted upon the eternal promontories of heaven above the stirs and shiftings of our lower system.