He had circled two-thirds and more when to his vigilant perceptions a hint came. Some ribbons of glossy weed hanging from shoulder height stirred a trifle overmuch in their shelter to the touch of wind. Instantly the wary boy thrust a hand through and encountered, not rock, but a void behind; he parted the thick fall of weed, and a narrow cleft was uncurtained, with blackness beyond, that to his peering dissolved into a cool, dim sea-cave, floored with water semilucent, roofed with darkness. Eagerly he pressed through, and dropped knee-deep into the still, dark water. Involuntarily his motions were subdued; silently, gently, he advanced into the midst of encompassing water and rock and darkness.
Such slight intrusion of daylight as the heavy kelp drapery allowed slanted into the glooms in slender, steady threads; from his wading hosts of wan lights broke and ran for the walls, casting up against them paler repeats; when he halted, faint sound from them wapped and sobbed, dominant items in a silence hardly discomposed by the note of far-off surf, so modulated by deflecting angles as to reach the ear faint and low as the murmur that haunts the curves of a shell.
For a long minute he stood in the midst motionless, while the chill of the water told on his blood, and the quiet darkness on his spirit. Mystery stepped here with an intimate touch, absent when under the open sky the sands presented their enigma. His heart did not fail; only resolution ordered it now, not impulse.
He spoke again to presumable ears. Only his own words he heard multiply in fading whispers through the hovering darkness. Silence came brooding back as he stood to hearken.
As his eyes dilated to better discernment, he suspected that an aisle withdrew, from a faint pallor, narrowing as it tended towards his height, explicable if water receded there, gathering vague translucence from some unseen source of light. To verify, he was advancing when a considerate notion turned him about. He left the dim cavern, returned in the blinding sunshine to the footprints, knelt by the last, and set his fingers in the sand for inscription. For a long moment he considered, for no words seemed effectual to deliver his complexed mind. When he wrote it was a sentence of singular construction, truly indicative of how vague awe and dread had uprisen to take large standing beside simple humane solicitude. He traced three large crosses, and then three words. Simple construing would read thus: 'In the name of the Father, the Son, and the Holy Ghost at your service.' Moderately content with that rendering, he transcribed it thrice on the rocks, graving with the branch of coral. At either end of the entrance gorge he set it, and again large and fair above the hidden mouth of the cave.
Back into darkness he dived to take up research, and wading towards the tremor of light, entered a long recess that led under low arches of rock, till light grew more definite, and the water-way ended, closed in by a breastwork of rock. But, this surmounted, the boy saw water again, of absolute green, dark as any stone of royal malachite. The level was lower by several feet, perhaps the true tide-level, perhaps yet another limited reservoir that the sea replenished daily. He slid down the scarp and went on, heartened by the increase of light.
The depth of the water varied, and the boy swam more often than he waded. The colour of the water varied; now it strengthened into a lucent green, now darkness threatened it, and he swam warily till it altered again, unaccountably. As his passing troubled the placid water, and ripples of colourless light, circling away from him, sent wavering lines of dim light rippling in response upon the sides of the passage, he caught vague, uncertain glimpses of dark rich colour mantling the rocks.
Suddenly, when light and colour were strongest, his way was barred, a wall of rock closing it abruptly. Baffled and perplexed, the boy swam to and fro in vain quest of an outlet, till his wits leapt on a fair surmise that inlets for light there must be submerged. Down he dived, groped, found justification in the arching rock, emerald flooded, struck boldly through it, and rose to the surface beyond.
A glory of light and colour dazzled him, momentarily repulsing his faculties from possession of a grand cavern, spacious, lofty, wonderful, worthy to be the temple of a sea-god.
He found recovery, he found footing, then straightway lost himself in wonder, for such splendours he had never dreamed could be.