Lacertines, most commonly found in Celtic Art, are interlaces created by animal forms. Interlaces are a two-dimensional decoration formed by a number of ribbons or straps woven into a complex, usually symmetrical design. The art is intricate, often incorporating animals into the elaborate twisting knots, and maze-like weavings. Some of the most common animals used in lacertines are snakes, birds, lions, and dogs.
The ornamental and decorative forms which are found in Irish illumination may be divided into a number of sections, among which are the highly conventional and rude representations of the human figure, as those of the Evangelists, angels, and other personages, all of which are drawn in a rude style, though often designed to fill admirably the spaces they occupy, and with a feeling of decorative fitness. While most of these figures are clearly developed from Byzantine sources, yet some of them have other characteristics that remind us of ancient Mesopotamian and Egyptian art. These decorative figures are of a type of weird and solemn imagery that is half ornamental and half symbolical, and have been used by the Irish scribes not only to decorate panels and other spaces, but often as terminals to bands or lines, or to the more important initials of the pages. Next in order may be noted the animal and bird forms which are largely used in Irish Celtic art. Although the class of ornament which is composed of these natural forms in combination with, or without, interlaced line endings is made up of what may be termed ” corrupted ” forms of animal life, with their mysterious lacertine twistings and crossings of linear ornament, it remains the most beautiful and most important kind among all others that is found in Irish art. Such varieties of animal life as eagles, ducks, dogs, and lions have been freely and skilfully used, their bodies, wings, feet, legs, and tails usually ending in lacertine work and twisted knots, which, though often highly involved in their mazy windings are never obscure or meaningless.
Some of the purely interlaced ribbon-like ornament is of extreme minuteness and resembles geometric weaving. This type is common enough in Byzantine decoration and also in many other historic styles of ornament, but still the Irish scribes have given to this ubiquitous variety a peculiarity of its own that enables us to distinguish it easily from similar ornament of its class. There is not much plant form used in Irish ornament, and where it is used it does not go much beyond the shamrock, or trefoil; sometimes a rose or daisy form of paterae is used in a very conventional way, that suggests the geometric setting of a circular jewelled brooch. Spirals and spiral-like forms are very common, including the triskele-shaped form which has been called the trumpet ” pattern, but this is quite likely to have been derived from Scandinavian symbolism. Lines, bands, dots, tartans, lozenges, frets, stepped – patterns, zigzags, chevrons, disks, meanders, and wheel-patterns are found as elements of Irish ornament, most of which are common to other styles, but the space divisions of the illuminated pages, and the original forms of the majestic initial letters and the methods of combination and distribution of the above simple elements in Irish ornamental compositions, together with the remarkable skill shown in the accurate drawing and marvellous execution, places such a work as the Book of Kells above and beyond any effort known in the art of ornamental illumination.
A word as to the colours used in the Irish illumination. We find red and yellow the most common, and are applied as body colours. Also a velvety black, green in some manuscripts, as well as blue, violet, and purple. The last three colours, however, are not very extensively used. The colours are mostly mineral in their origin, except the purple, which is usually obtained by a glaze of transparent madder over a blue body colour. ° The beautiful purples in the Book of Kells have been obtained in this method, and this purple colour has stood the test of time remarkably well. It may be mentioned that the ancient Irish and Welsh also obtained a beautiful purple from a species of small shell-fish like the cockle, but only in minute quantities, and similar perhaps to the Tyrian purple, which was also obtained from a shell-fish. Down to recent times the Irish peasantry obtained a coarser kind of purple, called, in Irish, corcur, from a rock lichen and used this for dyeing cloth. We are more inclined to the belief that neither of the two last-mentioned purples were used in the Book of Kells, as they would not have kept their colour so well as the purple in that book, which was clearly obtained by means of a transparent glaze of a madder-crimson over a blue ground. The bright yellow so common in the Book of Kells, was probably a mixture of opaque stanniferous, or tin white, or possibly zinc white, and a yellow derived from the saffron plant, which the ancient Irish used very much to dye their woollen garments. In any case, there are no lead or chromate pigments employed in the illumination of this magnificent book, notwithstanding the assertion of some critics, that lead colours were used, for if so, the red and yellow colours would have darkened greatly, and otherwise changed their hues centuries ago, and not have remained in their comparatively brilliant state at the present day to reflect their lustre and beauty.