They swam together in the deep little pool that covered half the cave-floor. He sat and watched her, later, while she disported herself alone, as a girl of our world might dance for her audience of one; a slim, green-and-coral-tinted nymph at play. He saw that she swam under the surface for several times the length he could manage; but she always came up breathless and very human. He saw her limbs flashing in the water with a silent, gliding grace; her tangled, tawny hair floating like seaweed. Her eyes were often laughing; dancing like the sea in the moonlight under a soft, fair night-breeze. She lay in the shallow water at its edge, her hair tumbling over her back; her shoulders and head raised, elbows down with chin propped by her hands. Her eyes dancing at him-- “Flinging back a million moonbeams, the tropic sea reminds me of thine eyes.” He murmured it. “That’s the way you look, Nereid. Oh, if you could only understand me.” She seemed to like it. “Say--that--” Her voice was soft, with liquid tones. “Say--that--” She thought for a space. “Say that--one time more--” He said it again. She came up from the water, and sat beside him, abruptly serious. The water dripped from her green robe; her tawny hair dripped with it. She was abruptly serious. She understood far more than he realized; she could talk, with long spaces of thought between the words. He stared into her eyes now when they were neither laughing, nor timorous, and saw there an intelligence as great as his own. Different, with all its knowledge different, and yet very much the same. He caught through those sea-green windows, a glimpse of the girl herself. Purposeful, anxious, apprehensive, not for herself, or himself, or anything of their own concerns, but something greater. And that evening, or the next, or both, she began giving him fragments of strange and startling things. He had been in his mind following the probable course of our Dolphin. He knew our plans; he could estimate that at midnight of August 14, we would very likely be at our closest point to him. And it was that night that he got out his sending instrument. With Nereid sitting beside him, he connected it. He saw anew, the real girl which was Nereid. Her glance, quickly intelligent, following all his strange movements; the solemn intentness with which she watched him carrying out their agreed-upon plans. For there was between her and Arturo now a mutual, secret, absorbing purpose. And for all their youth they executed it unswervingly.