The somewhat realistic way of representing the Evangelists as aged white-haired men, which occurs in Byzantine manuscripts, in the Carolingian _Gospels_ is replaced by a more conventional treatment, and thus they are as a rule represented as youthful, beardless men of an idealized type. The general treatment of the figure is flat, with little or no light and shade or modelling of any kind. The drapery is represented by strong, dark lines applied over a flatly laid wash of pigment. The painter first drew in his outlines with a fine brush dipped in red, and then filled in the intermediate spaces with a wash of colour mixed with a large proportion of gummy medium, so that a very glossy, lustrous surface was produced. The folds of the drapery and the rest of the internal drawing of the figures were put in after the application of the flat ground colour. This method very much resembles the process of the early Greek vase-painters. In order to give richness of effect by the use of a thick body of colour the illuminator commonly applied his flat tints in two or even three distinct washes, a method which is recommended by Theophilus[50] and other early writers on the technique of illumination. _Gospels at Vienna._ Another _Book of the Gospels_ which belonged to Charles the Great, now preserved in the Imperial Treasury at Vienna, is decidedly inferior as a work of art to the Paris manuscript mentioned above. In it the influence of the enfeebled Roman style is much stronger; the detail is far less refined and decorative, in spite of a copious use of burnished gold. This inferiority is due mainly to the absence of that Northumbrian influence, to which the best Carolingian manuscripts owe so much of their beauty. _Successors of Charles._ _Manuscripts of the later Carolingian school._ Under Charles the Great's successors the art of illuminating manuscripts continued to flourish, and, in the ninth century, under his grandsons Lothair and Charles the Bald, reached the climax of its development. During this century decorative splendour of a very high order was reached, in spite of there being very little advance in the power of rendering the human form. Gold, silver, ultramarine and brilliant pigments of all kinds were skilfully used; the subjects for miniatures became more varied, and detail was more delicate and highly finished[51]. _Portrait figures._ Portraits of the kings are often introduced at the beginning of books of this period, a fashion which in later times was extended to other than royal patrons of art and learning. A great number of places, chiefly Benedictine monasteries in France, became active centres for the production of fine illuminated manuscripts. Among them some of the principal places were Paris, St Denis, Rheims, Verdun, Fontanelle, and the two Abbeys of St Martin at Tours and Metz.