Trinity Sunday 
Trinity Sunday is a feast celebrated a week after Pentecost. Unlike other feasts it celebrates a doctrine - that of the three persons in one God. As this is a mystery, it is not something I have to explain - thank goodness! Interestingly it is said that the Eastern churches do not have a feast of the Trinity as it is celebrated at every Eucharist. 
The Trinity is familiar to many of us in the form of the sign of the cross - we pray 'In the name of the Father and of the Son and of the Holy Spirit' or in the prayer 'Glory be to the Father and to the Son and to the Holy Spirit, as it was in the beginning, is now and ever shall be, world without end. Amen.' In this week's second reading St. Paul writes 
'The grace of the Lord Jesus Christ, the love of God and the fellowship of the Holy Spirit be with you all.' 
It can be so easy to take this concept of Trinity for granted because of its familiarity. The Trinity is God, is one person in essence but distinct in person. Each person of the Trinity stands alone but is still one with the others. 
Some have explained the Trinity as the love between the Father and the Son. In art through the centuries the Trinity has been pictured as a triangle or as a shamrock or three-petalled flower. One piece of art called the Trinity was created in the fifteenth century and has become popular in recent years, Rublev's icon - pictured here. It is not of the Father, Son and Spirit but of the three angels who visited Abraham at Mamre. However, the picture is full of symbolism and is interpreted as being an icon of the Trinity. 
During this week it is worth reflecting on the icon, and the mystery of the Trinity and especially the love of God for the Son - and each one of us. 
For more information about the symbolism of the icon see: 
Sr. Margaret Mattison