"The holy Eucharist completes
Christian initiation. Those who have been raised to the dignity of
the royal priesthood by
Baptism and configured more deeply to Christ by
Confirmation participate with the whole community in the Lord's
own sacrifice by means of the Eucharist.
" ... The Lord, having loved those
who were his own, loved them to the end. Knowing that the hour had
come to leave this world and return to the Father, in the course of
a meal he washed their feet and gave them the commandment of love.
In order to leave them a pledge of this love, in order never to
depart from his own and to make them sharers in his Passover, he
instituted the Eucharist as the memorial of his death and
Resurrection, and commanded his apostles to celebrate it until his
return; 'thereby he constituted them priests of the New Testament."
Catechism of the Catholic Church, paragraphs 1322 & 1337