19. It is to this mode of destruction the Assyrian kings allude in their annals by the continually recurring phrase: "I destroyed their cities, I overwhelmed them, I burned them in the fire, _I made heaps of them_." However difficult it is to get at the treasures imbedded in these "heaps," we ought not to repine at the labor, since they owe their preservation entirely to the soft masses of earth, sand and loose rubbish which have protected them on all sides from the contact with air, rain and ignorant plunderers, keeping them as safely--if not as transparently--housed as a walnut in its lump of candied sugar. The explorers know this so well, that when they leave the ruins, after completing their work for the time, they make it a point to fill all the excavated spaces with the very rubbish that has been taken out of them at the cost of so much labor and time. There is something impressive and reverent in thus re-burying the relics of those dead ages and nations, whom the mysterious gloom of their self-erected tombs becomes better than the glare of the broad, curious daylight. When Layard, before his departure, after once more wandering with some friends through all the trenches, tunnels and passages of the Nimrud mound, to gaze for the last time on the wonders on which no man had looked before him, found himself once more on the naked platform and ordered the workmen to cover them up again, he was strongly moved by the contrast: "We look around in vain," says he, "for any traces of the wonderful remains we have just seen, and are half inclined to believe that we have dreamed a dream, or have been listening to some tale of Eastern romance. Some, who may hereafter tread on the spot when the grass again grows over the Assyrian palaces, may indeed suspect that I have been relating a vision." [Illustration: 27.--WINGED BULL. (Perrot and Chipiez.)]