The pavement masters worked in varying methods. The first of these was the joining together of large flat pieces of marble, cut in the shapes of the general design, and then outlining on them an actual black drawing by means of deeply cut channels, filled with hard black cement. The channels were first cut superficially and then emphasized and deepened by the use of a drill, in a series of holes. [Illustration: DETAIL OF PAVEMENT, BAPTISTERY, FLORENCE] Later workers used black marbles for the backgrounds, red for the ground, and white for the figures, sometimes adding touches of yellow inlay for decorations, jewels, and so forth. Some of the workers even used gray marble to represent shadows, but this was very difficult, and those who attempted less chiaroscuro were more successful from a decorator's point of view. This work covered centuries. The earliest date of the ornamental work in Siena is 1369. From 1413 to 1423 Domenico del Coro, a famous worker in glass and in intarsia, was superintendent of the works. The beauty and spirit of much of the earlier inlay have been impaired by restoration, but the whole effect is unique, and on so vast a scale that one hesitates to criticize it just as one hesitates to criticize the windows at Gouda. One compartment of the floor is in genuine mosaic, dating from 1373. The designer is unknown, but the feeling is very Sienese; Romulus and Remus are seen in their customary relation to the domesticated wolf, while the symbolical animals of various Italian cities are arranged in a series of circles around this centrepiece. One of the most striking designs is that of Absalom, hanging by his hair. It is in sharp black and white, and the foliage of the trees is remarkably decorative, rendered with interesting minutiae. This is attributed to Pietro del Minella, and was begun in 1447. A very interesting composition is that of the Parable of the Mote and the Beam. This is an early work, about 1375; it shows two gentlemen in the costume of the period, arguing in courtly style, one apparently declaiming to the other how much better it would be for him if it were not for the mote in his eye, while from the eye of the speaker himself extends, at an impossible angle, a huge wedge of wood, longer than his head, from which he appears to suffer no inconvenience, and which seems to have defied the laws of gravitation! The renowned Matteo da Siena worked on the pavement; he designed the scene of the Massacre of the Innocents--it seems to have been always his favourite subject. He was apparently of a morbid turn.