The Feast of Corpus Christi, sometimes known as, the Solemnity of the Most Holy Body and Blood of Christ. It celebrates the Real Presence of the Body and Blood, Soul and Divinity of Jesus Christ in the Eucharist.
The universal celebration of the feast of Corpus Christi was proposed by Saint Thomas Aquinas, to create a feast focused on the Holy Eucharist, showing the love, happiness and power of the Eucharist being the Body, Blood, Soul and Divinity of Jesus Christ, to Pope Urban IV in 1264.
Saint Juliana of Liège, was dedicated to Eucharistic worship and caring of the poor, she had a vision of Christ in which she was instructed to plead for the institution of the feast of Corpus Christi and so began to plea for such a feast to be made. Robert de Thorete, Bishop of Liège, ordered in 1246 a celebration of Corpus Christi to be held in the diocese each year thereafter on the Thursday after Trinity Sunday, the first such celebration occurred at St Martin's Church (Liège) the same year.
Corpus Christi is a moveable feast, celebrated on the Thursday after Trinity Sunday or, in countries where it is not a holy day of obligation, on the following Sunday.