When Jesus instituted the sacrament of the Eucharist at the Last Supper, he united himself to one of the most necessary human activities for survival, eating and drinking. Just as we cannot live without food and water, we cannot gain eternal life without Jesus Christ.
John 6:53-58, “So Jesus said to them, “Truly, truly, I say to you, unless you eat the flesh of the Son of Man and drink his blood, you have no life in you. Whoever feeds on my flesh and drinks my blood has eternal life, and I will raise him up on the last day. For my flesh is true food, and my blood is true drink. Whoever feeds on my flesh and drinks my blood abides in me, and I in him. As the living Father sent me, and I live because of the Father, so whoever feeds on me, he also will live because of me. This is the bread that came down from heaven, not like the bread the fathers ate and died. Whoever feeds on this bread will live forever.”