Besides that of perfecting a special process, to Luca della Robbia must be assigned the credit of paving the way to the revival which culminated in the products of Gubbio. The distinction between mezza-majolica and majolica must not be forgotten, viz., that the former name was originally applied to wares covered with a white slip, then painted, lead-glazed, and lustred, and the latter to tin-enamelled ware similarly lustred. The latter was thus the highest representative of the combination of two processes, both of Oriental origin. The application of metallic lustre was Persian. Stanniferous enamel was successively Egyptian, Babylonian, and Saracenic--the Saracens undoubtedly acquiring a knowledge of it in Persia, where the beautiful silicious glaze kept it in subordination. The Moors in Spain brought it more freely into use in decoration, and with Luca della Robbia, who perfected the process still farther, raised it from the desuetude into which it had fallen in Italy, where, however, it was already known to Saracenic settlers and their pupils. [Illustration: Fig. 211.--Siena Vase. (South Kensington Museum.)] With this recapitulation of the beginnings of real Italian majolica, we may now continue our history. The impetus Italian ceramic art received from foreign contact, and from the knowledge acquired by trade, was kept up by the wisdom and devotion to the cause of art manifested by several of the ducal houses. From Pesaro, under the house of Sforza, from Urbino, under that of Montefeltro, and from Florence and Chaffagiolo, under the Medicis, and from other centres, the art spread over all Italy. It is, therefore, by inquiries at these places that our investigations must be continued. Leaving out of view the questions as to the priority of Chaffagiolo to Faenza and Pesaro’s precedence in metallic lustring, we may begin with Tuscany.