The history of the art of enamelling is very imperfectly known, and the paucity of extant specimens makes the investigation the more difficult. The canvas upon which these pictures were laid consisted of plates of the precious metals, the smaller works being laid upon gold or silver, the larger on copper. As a natural consequence it happened that as soon as they were antiquated or had served their turn, they were lightly cast into the melting-pot, save where they were protected by some peculiar veneration. Hence it has come to pass that a favourite art of the Dark and Middle Ages, which we have reason to believe was for centuries very prolific (until it was superseded by the increased vigour of painting and sculpture in the fourteenth century), is now represented by a few specimens only, and its history is hard to retrace. I shall make no attempt to supply this want, and shall only rehearse a few interesting facts which the present investigation has brought to my knowledge. Origins I leave to specialists: but this I may say, that such evidence as the present enquiry has brought within the circle of my observation seems to suggest a Keltic source for the Enamel in our Jewel. The earliest mention of enamel to which we can confidently point is found in the book of Philostratus entitled _Pictures_ (Icones, Εἰκόνες). This author was a Greek rhetorician and connoisseur in Art, who came to Rome (A.D. 200) in the reign of Severus, attracted by the Court of Julia Domna, who (in the words of Gibbon) was the patroness of every art and the friend of every man of genius. In his _Icones_ he makes pictures the text of his elegant and fashionable discourse. Whether his pictures were real or imaginary is a matter of no consequence to our present purpose. The picture in which we are interested is one that represents a Meet for a Boar-hunt. The writer comments upon the well-equipped company, the horses and their riders, in the splendour of their get-up for the sport, drawing special attention to the curiosity and costliness of their horse-trappings. Their bits are silvern, and their head-stalls are decorated with gold and enamelled colours. For the production of these colours it is said that ‘the barbarians who dwell in the ocean do smelt them upon heated copper, and that in cooling they do set and harden and keep the design[20].’ It has been questioned who are meant by the barbarians in the ocean. Modern French writers have generally applied it to the Gauls; but Olearius, the editor of Philostratus (1709), understood the Keltic peoples; and certainly the expression appears more applicable to the British Isles than to Gaul. Moreover, it is in Britain, and not in Gaul, that enamelled horse-trappings have been found. Some of these may be seen in the Ashmolean, and more in the British Museum.