Joseph Campbell thought the peculiar cross with circle represented chakra ascension, and quoted WBYeats' line "ancient Ireland knew it all," in describing his theory of Gaelic Ireland's Tibetan-like achievements at spiritual culture.
A Scottish researcher and yachtsman, however, has patented the Celtic cross as a tool--re-discovered---he claims, and which he thinks useful in navigation, astronomy, surveying, cartography and time keeping. Surprisingly, the UK patent office concurs on the uniqueness of Crichton E M Miller's discovery; and he received his first of two patents in November 2000.
According to his application, the Celtic cross is something like a combination of the quadrant and astrolabe. He has used his instrument to tell the time and locate latitude and longitude. With it one can measure the angle of stars, calculate solstice and equinox, and locate the earth's North and South poles.
In 1978, the British sailor Tim Severin proved it possible that Saint Brendan discovered America by recreating a sea journey across the Atlantic in only a leather currach like the one Bréanainn (as he would have spelt it) used in the 6th century, 60 generations ago and 900 years before Columbus.
The clever Kerryman had all the tools he needed to confront the promised lands beyond the void.