And colours, read the history of their stars. Year after year, the slow sure records grow. Awaiting their interpreter. They shall see it, Our sons, in that far day, the swift, the strong, The triumphing young-eyed runners with the torch. No deep-set boundary-mark in Space or Time Shall halt or daunt them. Who that once has seen How truth leads on to truth, shall ever dare To set a bound to knowledge? "Would that he knew" --So thought the visitant at that shadowy shrine-- "Even as the maker of a song can hear With the soul's ear, far off, the unstricken chords To which, by its own inner law, it climbs, Would that my father knew how younger hands Completed his own planetary tune; How from the planet that his own eyes found The mind of man would plunge into the dark, And, blindfold, find without the help of eyes A mightier planet, in the depths beyond." Then, while the reeds, with quiet melodious pace Followed the dream, as in a picture passed, Adams, the boy at Cambridge, making his vow By that still lamp, alone in that deep night, Beneath the crumbling battlements of St. John's, To know why Uranus, uttermost planet known, Moved in a rhythm delicately astray From all the golden harmonies ordained By those known measures of its sister-worlds. Was there an unknown planet, far beyond, Sailing through unimaginable deeps And drawing it from its path? Then challenging chords Echoed the prophecy that Sir John had made, Guided by his own faith in Newton's law: _We have not found it, but we feel it trembling Along the lines of our analysis now As once Columbus, from the shores of Spain, Felt the new continent._ Then, in swift fugues, began A race between two nations for the prize Of that new world. Le Verrier in France, Adams in England, each of them unaware Of his own rival, at the selfsame hour Resolved to find it. Not by the telescope now! Skies might be swept for aeons ere one spark Among those myriads were both found and seen To move, at that vast distance round our sun. They worked by faith in law alone. They knew The wanderings of great Uranus, and they knew The law of Newton. By the midnight lamp, Pencil in hand, shut in a four-walled room, Each by pure thought must work his problem out,-- Given that law, to find the mass and place Of that which drew their planet from his course.