A shadow stood on the piazza, in the semi-darkness, at the appointed hour; two other shadows flitted forward to meet it, and silently down the bank, into the boat, and out upon the lonely glimmering reaches of the water.  Nobody spoke; the midnight capture of no fort was ever effected with more phantom-like noiselessness than now went to surprise the Vestals of the Lake; only as two hands touched for an instant, a strange thrill, like fire, quivered through each and tore them apart more swiftly than two winds might cross each other’s course.  Helen Heath was drowsy and half-nodding in the bow, nodding with the more ease that it was still so dark and that Mr. Raleigh’s back was toward her.  Mrs. Laudersdale reclined in the stern.  Mr. Raleigh once in a while sent them far along with a strong stroke, then only an occasional plash broke the charm of perfect stillness.  Ever and anon they passed under the lee of some island, and the heavy air grew full of idle night-sweetness; the waning moon with all its sad and alien power hung low,—­dun, malign, and distant, a coppery blotch on the rich darkness of heaven.  They floated slowly, still; now and then she dipped a hand into the cool current; now and then he drew in his oars, and, bending forward, dipped his hand with hers.  The stars retreated in a pallid veil that dimmed their beams, faint lights streamed up the sky,—­the dark yet clear and delicious.  They paused motionless in the shelter of a steep rock; over them a wild vine hung and swayed its long wreaths in the water, a sweet-brier starred with fragrant sleeping buds climbed and twisted, and tufts of ribbon-grass fell forward and streamed in the indolent ripple; beneath them the lake, lucid as some dark crystal, sheeted with olive transparence a bottom of yellow sand; here a bream poised on slowly waving fins, as if dreaming of motion, or a perch flashed its red fin from one hollow to another.  The shadow lifted a degree, the eye penetrated to farther regions; a bird piped warily, then freely, a second and a third answered, a fourth took up the tale, blue-jay and thrush, catbird and bobolink; wings began to dart about them, the world to rustle overhead, near and far the dark prime grew instinct with sound, the shores and heavens blew out gales of melody, the air broke up in music.  He lifted his oars silently; she caught the sweet-brier, and, lightly shaking it, a rain of dew-drops dashed with deepest perfume sprinkled them; they moved on.  A thin mist breathed from the lake, steamed round the boat, and lay like a white coverlet upon the water; a light wind sprang up and blew it in long rags and ribbons, lifted, and torn, and streaming, out of sight.  All the air was pearly, the sky opaline, the water now crisply emblazoned with a dark and splendid jewelry,—­the paved-work of a sapphire; a rosy fleece sailed across their heads, some furnace glowed in the east behind the trees, long beams fell resplendently through and lay beside vast shadows, the giant firs stood black and intense against