But the scene is widely different at low tide.  A fall of eighteen or twenty inches is enough to show ground over the greater part of the Lagoon; and at the complete ebb the city is seen standing in the midst of a dark plain of sea-weed, of gloomy green, except only where the larger branches of the Brenta and its associated streams converge toward the port of the Lido.  Through this salt and sombre plain the gondola and the fishing-boat advance by tortuous channels, seldom more than four or five feet deep, and often so choked with slime that the heavier keels furrow the bottom till their crossing tracks are seen through the clear sea-water like the ruts upon a wintry road, and the oar leaves blue gashes upon the ground at every stroke, or is entangled among the thick weed that fringes the banks with the weight of its sullen waves, leaning to and fro upon the uncertain sway of the exhausted tide.

The scene is often profoundly oppressive, even at this day, when every plot of higher ground bears some fragment of fair building:  but, in order to know what it was once, let the traveller follow in his boat at evening the windings of some unfrequented channel far into the midst of the melancholy plain; let him remove, in his imagination, the brightness of the great city that still extends itself in the distance, and the walls and towers from the islands that are near; and so wait, until the bright investiture and sweet warmth of the sunset are withdrawn from the waters, and the black desert of their shore lies in its nakedness beneath the night, pathless, comfortless, infirm, lost in dark languor and fearful silence, except where the salt runlets plash into the tideless pools, or the sea-birds flit from their margins with a questioning cry; and he will be enabled to enter in some sort into the horror of heart with which this solitude was anciently chosen by man for his habitation.

They little thought, who first drove the stakes into the sand, and strewed the ocean reeds for their rest, that their children were to be the princes of that ocean, and their palaces its pride; and yet, in the great natural laws that rule that sorrowful wilderness, let it be remembered what strange preparation had been made for the things which no human imagination could have foretold, and how the whole existence and fortune of the Venetian nation were anticipated or compelled, by the setting of those bars and doors to the rivers and the sea.  Had deeper currents divided their islands, hostile navies would again and again have reduced the rising city into servitude; had stronger surges beaten their shores, all the richness and refinement of the Venetian architecture must have been exchanged for the walls and bulwarks of an ordinary seaport.  Had there been no tide, as in other parts of the Mediterranean, the narrow canals of the city would have become noisome, and the marsh in which it was built pestiferous.  Had the tide been only a foot or eighteen inches higher in its rise, the water access to the doors of the palaces would have been impossible; even as it is, there is sometimes a little difficulty, at the ebb, in landing without setting foot upon the lower and slippery steps:  and the highest tides sometimes enter the court-yards, and overflow the entrance halls.