This type of curvilinear abstraction is strongly associated with Celtic Art, which employed a range of abstract motifs including knots (eight basic types), interlace patterns, and spirals (including the triskele, or the triskelion). These motifs were not original to the Celts - many other early cultures had been utilizing these Celtic designs for centuries: see for instance the spiral engravings at the Neolithic Passage Tomb at Newgrange in Co Meath, created some 2000 years before the appearance of the Celts. However, it is fair to say that Celtic designers breathed new life into these patterns, making them much more intricate and sophisticated in the process. These patterns later re-emerged as decorative elements in early illuminated manuscripts (c.600-1000 CE). Later they returned during the 19th century Celtic Revival Movement, and the influential 20th century Art Nouveau movement: notably in book-covers, textile, wallpaper and chintz designs by the likes of William Morris (1834-96) and Arthur Mackmurdo (1851-1942). Curvilinear abstraction is also exemplified by the "infinite pattern", a widespread feature of Islamic Art.