5. The human figure is frequently introduced, but it is subjected to the rigidity of the curved lines noticeable in the interlacings and spirals. Herein Irish art, which is primarily _ornamental_, differs from classic art, which is _representative_. The Irish artist aimed at symmetry and hence the right side of the face is generally a reproduction of the left. 6. In nearly all the art of the period under consideration the ground is divided into panels, or geometrical compartments—an arrangement whereby the artist whether working on vellum, metal, leather or stone was free to introduce any of the foregoing characteristics without marring the harmony and uniformity of the design.[445] Irish art attained its highest excellence in four branches, namely, writing and illumination of manuscripts, metal work and stone carving. In a previous chapter were discussed the characteristics of the Irish style of handwriting and the part played by the monastic schools in its development so we pass on to consider the other three departments of art work. ILLUMINATION: Shortly after the Irish monks became skilled penmen they began to illuminate their books with brilliant colours which they learned to combine into elaborate and harmonious designs. This art reached its most perfect stage of development at the close of the eighth or beginning of the ninth century. The monks were wont to lavish all the wealth of their artistic skill on books containing the whole or portions of the Holy Scriptures. As instances of this style of illuminated MSS. the _Psalter of ColmCille_, the _Book of Dimma_, the _Book of Armagh_, and, above all, the _Book of Kells_ should be mentioned. While each of these books has many merits the book which has compelled the admiration yet defied the imitation of every European artist is the _Book of Kells_. Describing this venerable volume which was written and illuminated about the middle of the ninth century, Sir Edward O’Sullivan writes as follows:[446] “Its weird and commanding beauty; its subdued and goldless colouring; the baffling intricacy of its fearless designs; the clean unwavering sweep of rounded spiral; the creeping undulations of serpentine forms that writhe in artistic profusion throughout the mazes of its decorations; the strong and legible minuscule of the text; the quaintness of its striking portraiture; the unwearied reverence and patient labour which brought it into being, all of which combined to make the _Book of Kells_, have raised this ancient volume to a position of abiding pre-eminence amongst the illuminated MSS. of the world.” Other artists are equally emphatic in their praises of the work of Irish artists during the period under consideration.