Celtic Art in the Global Village, continued

"The reason why interlaced-work is characteristic of early Christian decoration almost throughout the whole of Europe, whilst spirals, key-patterns, foliage etc., are confined to particular areas, I believe to be because the number of distinct patterns that can be produced from interlaced work is far greater than those which can be got from any other class of ornament. "

He also noted that the diagonal grid - derived from primitive geometric pattern - was common to key patterns as well as knot work patterns. I venture to think that (the key pattern) may have been suggested by the Greek or Roman fret, and that the essentially Celtic character imparted to it was in the placing of the guiding lines in a diagonal direction with regard to the margin, instead of parallel to it. I believe the reason for this to be that exactly the same setting out diagram was used both for the interlaced-work and the key-pattern. It is often possible to trace the origins of key-patterns to the necessities of the methods of weaving textile fabrics; but in regard to the ones we are considering I am inclined to think that their beginnings are due to to the geometrical conditions imposed by the arrangement of the setting-out lines."

The same applies to knotwork, which is the outcome of the path of a diamond grid, rather than a representation of weaving.