This employment of gold and silver inks may be looked upon as the first step in the art of illumination as practised in the Middle Ages. And the preliminary to the use of metallic inks was attention to the tint of the vellum. The pioneers in this career of luxury no doubt had observed that very white vellum fatigued the eye. Hence, at first, they tinted or stained it with saffron, on one side at least, sometimes on both. Once begun, the tinting of the vellum extended to other colours. For works of the highest rank the favourite was a fine purple, the imperial colour of the Roman and Greek emperors. For chrysography, or gold-writing, the tint was nearly what we call crimson. For arguriography, or silver-writing, it became the bluish hue we call grape-purple. On the cooled purples vermilion ink was used instead of, or together with, the gold or silver. As the usage began with the Greeks, we may be sure that it came originally from Asia. The Emperor Nero, once having heard that an Olympic Ode of Pindar in letters of gold was laid up in one of the temples at Athens, desired that certain verses of his own should be similarly written and dedicated on the Altar of Jupiter Capitolinus at Rome. This was an imperial luxury several times repeated by other princes. After the official establishment of Christianity it became a common practice to have the greater liturgical books executed in the same costly fashion. And between the time of Constantine and that of Basil the Macedonian many a burning homily was directed against the custom, denounced as a sinful extravagance, which no doubt it was, but in vain until the fashion had worn itself out. It might fairly be expected, this being the case, that many examples of this kind of codex would still be in existence. But owing to war, fire, robbery, and other misfortunes but very few remain. One of the oldest and finest is the so-called _Codex Argenteus_, or Silver-book, now kept at Upsala, in Sweden, containing portions of the Gospels of the Mæsogothic Bishop Ulfilas. Originally the effect of the stamped or burnished silver on the rich purple of the vellum must have been very splendid, but now the action of the air has blackened it, as it has done in many other instances where silver was used in illumination. Even gold will gather tarnish, and in several such MSS. has turned of a rusty red. Gold ink was not invariably confined to tinted vellum; it was often used on the plain ground. The copy of the Old Testament in Greek, presented by the high priest Eleazar to King Ptolemy Philadelphus, was a roll of fine white vellum, upon which the text was written in letters of gold.