Clarke shivered; the white mist gathering over the river was chilly.

“It is wonderful indeed,” he said.  “We are standing on the brink of a strange world, Raymond, if what you say is true.  I suppose the knife is absolutely necessary?”

“Yes; a slight lesion in the grey matter, that is all; a trifling rearrangement of certain cells, a microscopical alteration that would escape the attention of ninety-nine brain specialists out of a hundred.  I don’t want to bother you with ‘shop,’ Clarke; I might give you a mass of technical detail which would sound very imposing, and would leave you as enlightened as you are now.  But I suppose you have read, casually, in out-of-the-way corners of your paper, that immense strides have been made recently in the physiology of the brain.  I saw a paragraph the other day about Digby’s theory, and Browne Faber’s discoveries.  Theories and discoveries!  Where they are standing now, I stood fifteen years ago, and I need not tell you that I have not been standing still for the last fifteen years.  It will be enough if I say that five years ago I made the discovery that I alluded to when I said that ten years ago I reached the goal.  After years of labour, after years of toiling and groping in the dark, after days and nights of disappointments and sometimes of despair, in which I used now and then to tremble and grow cold with the thought that perhaps there were others seeking for what I sought, at last, after so long, a pang of sudden joy thrilled my soul, and I knew the long journey was at an end.  By what seemed then and still seems a chance, the suggestion of a moment’s idle thought followed up upon familiar lines and paths that I had tracked a hundred times already, the great truth burst upon me, and I saw, mapped out in lines of sight, a whole world, a sphere unknown; continents and islands, and great oceans in which no ship has sailed (to my belief) since a Man first lifted up his eyes and beheld the sun, and the stars of heaven, and the quiet earth beneath.  You will think this all high-flown language, Clarke, but it is hard to be literal.  And yet; I do not know whether what I am hinting at cannot be set forth in plain and lonely terms.  For instance, this world of ours is pretty well girded now with the telegraph wires and cables; thought, with something less than the speed of thought, flashes from sunrise to sunset, from north to south, across the floods and the desert places.  Suppose that an electrician of today were suddenly to perceive that he and his friends have merely been playing with pebbles and mistaking them for the foundations of the world; suppose that such a man saw uttermost space lie open before the current, and words of men flash forth to the sun and beyond the sun into the systems beyond, and the voice of articulate-speaking men echo in the waste void that bounds our thought.  As analogies go, that is a pretty good analogy of what I have done; you can understand now a little of what