Catechism of the Catholic Church
“It is highly fitting that Christ should have wanted to remain present to his Church in this unique way. Since Christ was about to take his departure from his own in his visible form, he wanted to give us his sacramental presence; since he was about to offer himself on the cross to save us, he wanted us to have the memorial of the love with which he loved us ‘to the end,’ even to the giving of his life.”
Source: Catechism of the Catholic Church #1380