This Celtic shirt design incorporates a Shamrock at the cross’s center, further adding to its Irish identity. The Celtic Cross has different histories. One of the more popular is that St. Patrick or St. Declan melded the Christian cross with the pagan/Celtic sun to symbolize interaction between the cross and all it symbolizes and the sun, long a powerful pagan symbol of life, abundance and banishment of the darkness. It has also been adopted to symbolism Irish pride and remembrance of Irish roots.
The shamrock also has blended traditions, from the Druid/pagan view of the triple leaves aligning with the sacred number three to St. Patrick's use of it to represent the Holy Trinity. In the 19th century the shamrock evolved into a symbol of rebellion. Now it is more a symbol of Celtic/Irish heritage and the four-leaf variety is strongly associated with luck for those who find it.