There are miles and miles of it right up to the EMBANKMENT, the great and old SEA-WALL, which protects the houses of men.  You have but to eliminate that embankment to imagine what the whole countryside must have been like before it was raised, and the meaning of the Fens becomes clear to you.  The Fens were long ago but the continuation inland of this sea-morass.  The tide channels of the marsh were all of one kind, though they differed so much in size.  Some of these channels were small without name; some a little larger, and these had a local name; others were a little larger again, and worthy to be called rivers—­the Ouse, the Nen, the Welland, the Glen, the Witham.  But, large or small, they were nothing, all of them, but the scouring of tide-channels in the light and sodden slime.  It was the high tide that drowned all this land, the low tide that drained it; and wherever a patch could be found just above the influence of the tide or near enough to some main channel for the rush and swirl of the water to drain the island, there the villages grew.  Wherever such a patch could be found men built their first homes.  Sometimes, before men civic, came the holy hermits.  But man, religious, or greedy, or just wandering, crept in after each inundation and began to tame the water and spread out even here his slow, interminable conquest.  So Wisbeach, so March, so Boston grew, and so—­the oldest of them all—­the Isle of Ely.

The nature of the country (a nature at which I had but guessed whenever before this I had wandered through it, and which I had puzzled at as I viewed its mere history) was quite clear, now that I stood upon the wall that fenced it in from the salt water.  It was easy to see not only what judgments had been mistaken, but also in what way they had erred.  One could see why and how the homelessness of the place had been exaggerated.  One could see how the level was just above (not, as in Holland, below) the mean of the tides.  One could discover the manner in which communication from the open sea was possible.  The deeps lead out through the sand; they are but continuations under water of that tide-scouring which is the note of all the place inland, and out, far out, we could see the continuation of the river-beds, and at their mouths far into the sea, the sails.

A man sounding as he went before the north-east wind was led by force into the main channels.  He was “shepherded” into Lynn River or Wisbeach River or Boston River, according as he found the water shoaler to one side or other of his boat.  So must have come the first Saxon pirates from the mainland:  so (hundreds of years later) came here our portion of that swarm of Pagans, which all but destroyed Europe; so centuries before either of them, in a time of which there is no record, the ignorant seafaring men from the east and the north must have come right up into our island, as the sea itself creeps right up into the land through these curious crevices and draughts in the Fenland wall.