In the infancy of religious worship the altar took two distinct shapes; sometimes the form of a table, with a top of stone, wood, or metal supported by legs or by columns; sometimes it resembled an ancient tomb, or a long coffer, narrowed at the base, and surmounted by a similar covering, which invariably formed the upper portion, or the table, of the altar. In addition to altars, more or less monumental, which were fixtures in the churches, and which, from the earliest period, were placed under _ciboria_ (a kind of dais or canopy supported by columns), small portable altars were employed, in order to meet the requirements of the service. They were intended to accompany the bishops, or the ordinary clergy, who had to preach the faith in countries where no churches existed. These altars, which were alluded to when the Christian religion had made but slight progress, were no longer seen after it became general; but we again find them at the time of the Crusades, when pious pilgrims, who journeyed from place to place preaching the Gospel, were obliged to say mass in fields and public places, where the faithful assembled to hear them, and to “take up the cross.” M. Jules Labarte gives the following summary description of a portable altar of the twelfth century:--“It consists of a slab of lumachella marble, set in a box of gilt copper, 36 centimètres in height by 27 in width, and 3 in thickness. The top of the box is cut in such a manner as to leave uncovered the stone on which the chalice was placed during the celebration of mass.” Throughout all the periods of the Middle Ages, the ardent faith of which seemed to consider sufficient honour could never be rendered to the real presence of God in the holy sacrifice, the ornamentation of the altar was everywhere looked upon as an object of the most extraordinary pomp and of the most elevated artistic taste. Among the marvels of this kind we must name, as occupying a leading place, the gold altar of St. Ambrose, in Milan, which dates from 835, and those of the cathedrals of Basle and Pistoia, which belong to the eleventh and twelfth centuries. These gold altars, wrought with the hammer, were chased and sometimes enamelled, and in addition to remarkably well executed designs in carved work, taken from religious books, they usually also had on them portraits of the donors. The altars and tabernacles were executed with an equal amount of art and costliness; and from the earliest period of the fabrication or the importation of carpets, embroideries, and gold and silver fabrics, we see them employed for the purpose of covering, adorning, and of rendering more striking and imposing the altar and its accessories, to which the name of chancel was given (Fig. 20).