The characteristic of the finest pieces of Saxon jewellery of the Christian period is their ornamentation by means of cloisonné enamel. It has already been noticed that Anglo-Saxon jewels were decorated with gold wires, some twisted or beaded, or rolled up and plaited together, and soldered on to a thin gold plate; while others were flattened into strips forming compartments, which were filled with pieces of garnet or coloured glass cut to shape. When the spaces between strips, so disposed as to make up the outlines of figures or ornament, were filled with enamel paste and fired, the result was enamel of the cloisonné type. This cloisonné enamel naturally resulted as soon as the Saxon jeweller had mastered the art of fusing vitreous colours upon metal. From whom did he learn this art? Was enamelling introduced by the followers of Augustine from Rome or Byzantium, or did the Irish missionaries bring afresh into England an art of which the Celts were past masters? The question is one that cannot be answered; but it is not without interest to note the great influence of the Irish craftsmen on the art productions of the time. A remarkable development of goldsmiths' work in Ireland succeeded the introduction of Christianity. Enamel was largely employed in the decoration of early objects of ecclesiastical metal-work, and attained perfection in the translucent cloisonné enamel of the Tara brooch and the Ardagh chalice. The far-reaching influence and extraordinary activity of the Irish missionaries, many of them no doubt skilled goldsmiths, are well known. "Irish missionaries laboured among the Picts of the Highlands and among the Frisians of the northern seas. An Irish missionary, Columban, founded monasteries in Burgundy and the Apennines. The canton of St. Gall still commemorates in its name another Irish missionary."[19] The processes of their artistic metal-work must have made themselves felt wherever these Irish missionaries penetrated. The wandering scholars and artists of Ireland left both their books and their art-apprentices in England, as they had left them along the Rhine and the Danube. At Glastonbury, St. Dunstan, the patron saint of English smiths, lingered as a youth among the books with which the Irish missionaries had endowed the monastery, and associated doubtless with the monastic craftsmen who had learned the arts of their Celtic predecessors. [19] Green (J. R.), _Short history of the English People_ (1875 ed.), p. 21.