Today is known as ‘Low Sunday’ because it concludes the Easter Octave and in former times was the last day the newly baptised wore their white robes (Latin – ‘Dominica in Albis’).  The Gospel tells how the risen Lord appeared on this day to reassure Thomas that was truly alive and how he breathed the Holy Spirit on his gathered disciples giving them the power to forgive sins in his name.  It was to emphasise the importance of this gift that Our Lord appeared to a Polish nun, St Faustina Kowalska, and asked for a feast to be established on this day in honour of his Divine Mercy.