the possibility of passing out of sight of land

Three hours passed. The shore was twelve or fifteen miles behind, and looked like a blue cloud, for the summer haze hid the hills, more than would have been the case in clearer weather.
Another hour, and at last Felix, awakening from his slumberous condition, looked round and saw nothing but the waves. The shore he had left had entirely disappeared, gone down; if there were land more lofty on either hand, the haze concealed it. He looked again; he could scarcely comprehend it. He knew the Lake was very wide, but it had never occurred to him that he might possibly sail out of sight of land. This, then was why the mariners would not quit the islands; they feared the open water. He stood up and swept the horizon carefully, shading his eyes with his hand; there was nothing but a mist at the horizon. He was alone with the sun, the sky, and the Lake. He could not surely have sailed into the ocean without knowing it? He sat down, dipped his hand overboard and tasted the drops that adhered; the water was pure and sweet, warm from the summer sunshine.
There was not so much as a swift in the upper sky; nothing but slender filaments of white cloud. No swallows glided over the surface of the water. If there were fishes he could not see them through the waves, which were here much larger; sufficiently large, though the wind was light, to make his canoe rise and fall with their regular rolling. To see fishes a calm surface is necessary, and, like other creatures, they haunt the shallows and the shore. Never had he felt alone like this in the depths of the farthest forest he had penetrated. Had he contemplated beforehand the possibility of passing out of sight of land, when he found that the canoe had arrived he would probably have been alarmed and anxious for his safety. But thus stumbling drowsily into the solitude of the vast Lake, he was so astounded with his own discovery, so absorbed in thinking of the immense expanse, that the idea of danger did not occur to him.
Another hour passed, and he now began to gaze about him more eagerly for some sight of land, for he had very little provision with him, and he did not wish to spend the night upon the Lake. Presently, however, the mist on the horizon ahead appeared to thicken, and then became blue, and in a shorter time than he expected land came in sight. This arose from the fact of its being low, so that he had approached nearer than he knew before recognising it. At the time when he was really out of sight of the coast, he was much further from the hilly land left behind than from the low country in front, and not in the mathematical centre, as he had supposed, of the Lake. As it rose and came more into sight, he already began to wonder what reception he should meet with from the inhabitants, and whether he should find them as hard of heart as the people he had just escaped from. Should he, indeed, venture among them at all? Or should he remain in the woods till he had observed more of their ways and manners? These questions were being debated in his mind, when he perceived that the wind was falling.