Admirable, however, as the Paris of the present day appears to you, build up and put together again in imagination the Paris of the fifteenth century; look at the light through that surprising host of steeples, towers, and belfries; pour forth amid the immense city, break against the points of its islands, compress within the arches of the bridges, the current of the Seine, with its large patches of green and yellow, more changeable than a serpent's skin; define clearly the Gothic profile of this old Paris upon an horizon of azure, make its contour float in a wintry fog which clings to its innumerable chimneys; drown it in deep night, and observe the extraordinary play of darkness and light in this sombre labyrinth of buildings; throw into it a ray of moonlight, which shall show its faint outline and cause the huge heads of the towers to stand forth from amid the mist; or revert to that dark picture, touch up with shade the thousand acute angles of the spires and gables, and make them stand out, more jagged than a shark's jaw, upon the copper-coloured sky of evening. Now compare the two.