
St Patrick and his followers were summoned to Tara by the High King, Laoghaire following their lighting of the paschal fire at Slane. The painting illustrates the moment when Saint Patrick used the shamrock to explain the mystery of the Trinity to High King Laoghaire and the druids.
Background
This painting is one of six from the sanctuary of the College Chapel, depicting scenes from the lives of the Irish saints. The other paintings feature St Laurence O'Toole, St Brigid, St Malachy, St Columbanus and St Columba.

This photograph is taken from the organ gallery and illustrates how the painting of St Patrick is normally difficult to see, being situated directly behind the high altar, where the view is obstructed by the alabaster and marble reredos.
The original altar did not have such a high reredos, and many at the time said it was more in keeping with the scale of the Chapel. It was moved to Annaduff parish near Carrick-on-Shannon, County Leitrim, where It can still be seen.
The present altar and reredos dates from 1911, and features statues of the patrons of the four archdioceses. It was funded from the estate of Monsignor Gerald Molloy (1834 - 1906), who had a long association with the College.
Monsignor Molloy was Professor of Dogmatic and Moral Theology in St Patrick's College, appointed to that chair in 1857, and subsequently professor of Natural Philosophy, vice-rector and rector of the Catholic University, and vice-chancellor of the Royal University.