The Irish Celtic Knot is a symbol of the Holy Trinity used in early Christian illustrations from 400 BC to 800 AD. Also known as the Trinity Knot. This was used extensively in the Book of Kells, the world famous ancient monastic manuscript.
The Triskell is said to be the oldest symbol of spirituality. The design figures heavily in Irish Neolithic art, most notably at Newgrange, the prehistoric passage tomb in County Meath.