In remote times, when the inhabitants of this plain were few and uncivilized, the country formed but one immense morass, of which the chief part was incessantly inundated and made sterile by the waters of the sea.

Pliny the naturalist, who visited the northern coasts, has left us a picture of their state in his days.

"There," says he, "the ocean pours in its flood twice every day, and produces a perpetual uncertainty whether the country may be considered as a part of the continent or of the sea.

The wretched inhabitants take refuge on the sand-hills, or in little huts, which they construct on the summits of lofty stakes, whose elevation is conformable to that of the highest tides.

When the sea rises, they appear like navigators; when it retires, they seem as though they had been shipwrecked.