Nearly all the old literatures may be said to have been founded upon fable, and upon a basis and even superstructure of ignorance, that, however charming it may be, we have not now got, and could not keep if we had. The bump of wonder and the feeling of the marvelous,--a kind of half-pleasing fear, like that of children in the dark or in the woods,--were largely operative with the old poets, and I believe are necessary to any eminent success in this field; but they seem nearly to have died out of the modern mind, like organs there is no longer any use for. The poetic temperament has not yet adjusted itself to the new lights, to science, and to the vast fields and expanses opened up in the physical cosmos by astronomy and geology, and in the spiritual or intellectual world by the great German metaphysicians. The staple of a large share of our poetic literature is yet mainly the result of the long age of fable and myth that now lies behind us. "Leaves of Grass" is, perhaps, the first serious and large attempt at an expression in poetry of a knowledge of the earth as one of the orbs, and of man as a microcosm of the whole, and to give to the imagination these new and true fields of wonder and romance. In it fable and superstition are at an end, priestcraft is at an end, skepticism and doubt are at an end, with all the misgivings and dark forebodings that have dogged the human mind since it began to relax its hold upon tradition and the past; and we behold man reconciled, happy, ecstatic, full of reverence, awe, and wonder, reinstated in Paradise,--the paradise of perfect knowledge and unrestricted faith.