Communion Antiphon, Jn 6:57:Whoever eats my flesh and drinks my blood remains in me and I in him, says the Lord. The Solemnity of the Body and Blood of Christ is observed on the Thursday following on the solemnity of the Most Blessed Trinity. Where the Solemnity of the Body and Blood of Christ is not observed as a Holy Day of obligation on Thursday, it is assigned to the Sunday after Trinity Sunday, which is then considered its proper day in the calendar.