Holy Communion commemorates Jesus' Last Supper with his disciples during Passover. Catholics believe that during this final meal, Jesus blessed the bread and wine and said, “This is my body ... This is my blood.” ... The bread and wine become the body, blood, soul and divinity of Jesus. The principal purpose of this sacrament is to increase sanctifying grace, repeatedly and often, through personal union with the Giver of grace Himself.
" For as often as you eat this bread and drink the cup, you proclaim the Lord's death until he comes." 1 Corinthians 11:23-26