Away up at the headwaters of the Missouri, near the British possessions, I found myself one afternoon rather unexpectedly on the shore of an ocean. At less than a gunshot from where I stood was as plainly defined a seabeach as one could wish to see. The eye could follow it in either direction, with all its bays, inlets and promontories, to the horizon. The sea was studded with islands, and these with tall trees of many kinds, both islands and trees being reflected in the water with absolute fidelity. On many of the islands were houses, showing white beneath the trees, and on one which lay farthest out seaward was a considerable city, with towers, domes and clusters of steeples. There were ships in the offing whose sails glistened in the sunlight and, closer in, several boats of novel but graceful design, crowded with human figures, moved smoothly among the lesser islands, impelled by some power invisible from my point of view, each boat attended by its inverted reflection "crowding up beneath the keel." It must be admitted that the voyagers were habited after a somewhat uncommon fashion--almost unearthly, I may say--and were so grouped that at my distance I could not clearly distinguish their individual limbs and attitudes. Their features were, of course, entirely invisible. None the less, they were plainly human beings--what other creatures would be boating? Of the other features of the scene--the coast, islands, trees, houses, city and ships hull-down in the offing--I distinctly affirm an absolute identity of visible aspect with those to which we are accustomed in the realm of reality; imagination had simply nothing to do with the matter. True, I had not recently had the advantage of seeing any such objects, except trees, and these had been mighty poor specimens, but, like Macduff, I "could not but remember such things were," nor had I forgotten how they looked.