. The first has been the canalisation, the
fencing in of the tideways; the second has been the banking out of the
general sea. The spring tides covered much of this land, and when they
retired left it drowned. Against their universal advancing sheet of
water a bank could be made. Such a bank cut off the invasion of the
hundreds of runnels, small and great, by which the more ordinary tides
that could not cover the surface had yet crept into the soil and soaked
it through.

When such a bank had been built, gates, as it were, permitted the water
to spend its force and also to use its ebb and flow for the draining of
the land beyond. The gates which let the tide pour up and down the main
ways became the new mouths of the main rivers; inland the courses of the
rivers (which now took all the sea and thus became prodigious) were
carefully guarded. Even before trenches were dug to drain the fields
around, earth was thrown up on either side of the rivers to confine them
each to one permanent channel; nor did the level of the rivers rise, or
their beds gets clogged; the strength of the tide sufficed for the
deepening of their channels. Into the rivers so fortified the other
waterways of the Fens were conducted.

By these methods alone much of the land was rendered habitable and
subject to the plough. Probably these methods were enough to make it all
it was in the Middle Ages. It was only far later, almost in our own
time, that water was gathered by trenches in the lowland beneath the
rivers and pumped out artificially with mills; nor is it quite certain
even now that this method (borrowed from Holland) is the best; for the
land, as I have said, is above and not below the sea.

Of these words, whose tradition is immemorial, the greatest, of course,
are the sea-walls.

Perhaps the river-walls came first, but the great bank which limited
and protected the land against the sea is also older than any history.

It is called Roman, and relics of Rome have been found in it, but it has
not the characteristic of Roman work. It runs upon no regular lines; its
contour is curved and variable. It is surely far older than the Roman
occupation. Earth, heaped and beaten hard, is the most enduring of
things; the tumuli all over England have outlasted even the monoliths,
and the great defensive mounds at Norwich and at Oxford are stronger and
clearer cut than anything that the Middle Ages have left. This bank,
which first made Fenland, still s