According to tradition, St. Patrick used a three-leaf shamrock to explain the concept of the Holy Trinity while preaching, with each leaf symbolizing the Father, the Son, and the Holy Spirit. This represented how these three distinct entities are all part of the same divine whole.

While it’s customary to wear green on St. Patrick’s Day, all historical depictions of St. Patrick show him dressed in blue robes. This is why blue was originally used in flags, sports uniforms, and coats-of-arms. However, over time, green became more popular, especially by the 17th century.

In Catholicism, the feast day of a saint is celebrated on the anniversary of their death, marking their ascension to heaven. St. Patrick passed away on March 17, which is why the holiday is celebrated on that day each year.

The tradition of drinking on St. Patrick’s Day is said to have started with St. Patrick himself, who encouraged everyone to have a “drop of the hard stuff” after an innkeeper was reluctant to serve whiskey. Although drinking was once prohibited on the holiday, the custom has since made a strong comeback.