The altar-screens, as we have seen, were the special activity of the period. M. Marcel Dieulafoy gives an excellent and concise account of the manner in which these important works were carried out by different sets of workmen, for it was rarely that all the processes necessary to the completion of a polychrome were undertaken by one artist. First and most important there was the tracer, afterwards called the assembler, the chief artist, who furnished the design both for the whole work and its ornaments of statuary and bas-reliefs, and also superintended its execution. To him the sculptors, ornamenters, master-masons, and master-carpenters were subordinate, but the painters, damaskers, and gilders were free from his control. Thus writes M. Marcel Dieulafoy: “The intervention of four successive brotherhoods of artists was required--1. _Tracers_, who later became known as _Architectural Assemblers_; 2. _Imagers_, who were the sculptors and carvers; 3. the _Eucaruadores_, the body-painters who coloured the flesh of the figures; 4. the _Estofadores_ and _Doradores_, who were respectively the stuff-painters and the gilders.” Just as the tracer had ascendency over and directed the work of the imagers--the sculptors and carvers--so the Eucaruadore, or flesh-artist, was the head of the polychrome workers, and directed the colourers of the stuff-painters and the gilders. His position was one of supreme importance, which is proved by the fact that it was not unusual for him to receive for his work as much as half of the entire sum paid. This is an interesting proof of the high esteem in which the art of polychrome was held. The Estofadores had not the same importance; their work was to paint the stuffs of the garments, generally on a background of gold, and also foliage and arabesques. The Doradores or gilders were their collaborators, and their special work, besides the gilding of the background, was to paint in “full-gilt” armour, &c., and to enrich with jewels; to their share also fell the art of damasking. Almost all the great painters of Spain were polychromists, and we find them collaborating with the sculptors. This custom continued far beyond the period we have been considering. Zurbaran, Murillo, Valdés Leal, and Pacheco coloured the statues of Gaspar Delgado and Montañés. Pacheco, the great historian, who was also a painter, especially extols the art of polychrome in several illuminating passages in his _Arte de la Pintura_. In one place he writes:--