me, in the darkness) that I was in a powerful current, and that this current set the wrong way.  Instantly a flood of new intelligence came.  Either I had unconsciously turned and was rapidly nearing the Rebel shore,—­a suspicion which a glance at the stars corrected,—­or else it was the tide itself which had turned, and which was sweeping me down the river with all its force, and was also sucking away at every moment the narrowing water from that treacherous expanse of mud out of whose horrible miry embrace I had lately helped to rescue a shipwrecked crew.  Either alternative was rather formidable.  I can distinctly remember that for about one half-minute the whole vast universe appeared to swim in the same watery uncertainty in which I floated.  I began to doubt everything, to distrust the stars, the line of low bushes for which I was wearily striving, the very land on which they grew, if such visionary tiring could be rooted anywhere.  Doubts trembled in my mind like the weltering water, and that awful sensation of having one’s feet unsupported, which benumbs the spent swimmer’s heart, seemed to clutch at mine, though not yet to enter it.  I was more absorbed in that singular sensation of nightmare, such as one may feel equally when lost by land or by water, as if one’s own position were all right, but the place looked for had somehow been preternaturally abolished out of the universe.  At best, might not a man in the water lose all his power of direction, and so move in an endless circle until he sank exhausted?  It required a deliberate and conscious effort to keep my brain quite cool.  I have not the reputation of being of an excitable temperament, but the contrary; yet I could at that moment see my way to a condition in which one might become insane in an instant.  It was as if a fissure opened somewhere, and I saw my way into a mad-house; then it closed, and everything went on as before.  Once in my life I had obtained a slight glimpse of the same sensation, and then too, strangely enough, while swimming,—­in the mightiest ocean-surge into which I had ever dared plunge my mortal body.  Keats hints at the same sudden emotion, in a wild poem written among the Scottish mountains.  It was not the distinctive sensation which drowning men are said to have, that spasmodic passing in review of one’s whole personal history.  I had no well-defined anxiety, felt no fear, was moved to no prayer, did not give a thought to home or friends; only it swept over me, as with a sudden tempest, that, if I meant to get back to my own camp, I must keep my wits about me.  I must not dwell on any other alternative, any more than a boy who climbs a precipice must look down.  Imagination had no business here.  That way madness lay.  There was a shore somewhere before me, and I must get to it, by the ordinary means, before the ebb laid bare the flats, or swept me below the lower bends of the stream.  That was all.