The land produced after this fashion has one enemy, to wit, the sea. Holland maintains its existence only by virtue of its dykes. In 1654 those in Jutland burst, and fifteen thousand of the inhabitants were swallowed up. One need only see the blast of the North swirl down upon the low level of the soil, wan and ominous:[9] the vast yellow sea dashes against the narrow belt of flat coast which seems incapable of a moment's resistance; the wind howls and bellows; the sea-mews cry; the poor little ships flee as fast as they can, bending almost to the gunwale, and endeavor to find a refuge in the mouth of the river, which seems as hostile as the sea. A sad and precarious existence, as it were face to face with a beast of prey. The Frisians, in their ancient laws, speak already of the league they have made against "the ferocious ocean." Even in a calm this sea is unsafe. "Before me rolleth a waste of water... and above me go rolling the storm-clouds, the formless dark gray daughters of air, which from the sea, in cloudy buckets scoop up the water, ever wearied lifting and lifting, and then pour it again in the sea, a mournful, wearisome business. Over the sea, flat on his face, lies the monstrous terrible North wind, sighing and sinking his voice as in secret, like an old grumbler, for once in good humor, unto the ocean he talks, and he tells her wonderful stories."[10] Rain, wind, and surge leave room for naught but gloomy and melancholy thoughts. The very joy of the billows has in it an inexplicable restlessness and harshness. From Holland to Jutland, a string of small deluged islands[11] bears witness to their ravages; the shifting sands which the tide drifts up obstruct and impede the banks and entrance of the rivers.[12] The first Roman fleet, a thousand sail, perished there; to this day ships wait a month or more in sight of port, tossed upon the great white waves, not daring to risk themselves in the shifting winding channel, notorious for its wrecks. In winter a breast-plate of ice covers the two streams; the sea drives back the frozen masses as they descend; they pile themselves with a crash upon the sandbanks, and sway to and fro; now and then you may see a vessel, seized as in a vice, split in two beneath their violence. Picture, in this foggy clime, amid hoar-frost and storm, in these marshes and forests, half-naked savages, a kind of wild beasts, fishers and hunters, but especially hunters of men; these are they, Saxons, Angles, Jutes, Frisians;[13] later on, Danes, who during the fifth and the ninth centuries, with their swords and battle-axes, took and kept the island of Britain.