The Celtic Insular style is most famous for its highly dense, intricate and imaginative decoration, which takes elements from several earlier styles.
From late Celtic art, sometimes known as the "Ultimate La Tène" style, come the love of spirals, triskeles, circles and other geometric motifs.
These were combined with animal forms probably mainly deriving from the Germanic version of the general Eurasian animal style, though also from Celtic art, where heads terminating scrolls were common. Interlace was used by both these traditions, as well as Roman art (for example in floor mosaics) and other possible influences such as Coptic art, and its use was taken to new levels in Insular art, where it was combined with the other elements already mentioned.
There is no attempt to represent depth in manuscript painting, with all the emphasis on a brilliantly patterned surface. In early works the human figure was shown in the same geometric fashion as animal figures, but reflections of a classical figure style spread as the period went on, probably mostly from the southern Anglo-Saxon regions, though northern areas also had direct contacts with the Continent. The origins of the overall format of the carpet page have often been related to Roman floor mosaics,Coptic carpets and manuscript paintings, without general agreement being reached among scholars.
C. R. Dodwell, on the other hand, says that in Ireland "the Insular style continued almost unchallenged until the Anglo-Norman invasion of 1170; indeed examples of it occur even as late as the thirteenth and fourteenth centuries".
Celtic motifs most commonly recognized are the knotworks, key patterns, and spirals found in the illuminated manuscripts of the Early Medieval Period. The most famous manuscript is the Book of Kells. Some others are the Lindisfarne Gospels, the Book of Durrow, and the Durham Gospels. Before the period of the manuscripts the Celts carved symbol stones and created a wide variety of jewelry for themselves and their horses.
Since the Irish Celts held back the Roman armies from conquering them, they kept alive the Celtic Arts. There have been several revival periods. In the United States one of those revivals happen around the Revolutionary War.
Geometric motifs have always been prominent in Celtic artwork. Some of the motifs or symbols date back to 3000 BC and can still be seen today on stone carvings. Newgrange in Ireland, is one of the oldest burial mounds in Europe and is highly decorated with stone (see picture on the right) carvings depicting spirals, lozenges, chevrons and key patterns.
Single Spiral The single spiral is the oldest and most recorded of these motifs. It has symbolized the concept of growth, expansion, and cosmic energy, depending on the culture in which it is used. To the ancient inhabitants of Ireland, the spiral was used to represent their sun.
Sun Spirals A loosely wound anti-clockwise spiral represented the large summer sun.
A tightly wound, clockwise spiral represented their shrinking winter sun.
Double Spiral A double spiral is used to represent the equinoxes, when day and night are of equal length
Double Centered Spiral The dual centered spiral is also prolific in stone carvings. It has associations with motifs from other cultures such as the Yin Yang symbol. It signifies the duality of nature and balance.
Triple Centered Spiral Triple centered spirals were used by the early Christian monks in their illuminated manuscripts. The motif depicts a trinity of spirals emanating from a single source and may well have been used by the monks to represent the Christian holy Trinity.
Since Celtic Art is alive it will continue to evolve yet it will retain the influence of the ancient world such as the manuscripts, the Scottish symbol stones, and the spiraled carved stones found in dolmens.