While he was at table in his house,
many tax collectors and sinners sat with Jesus and his disciples;
for there were many who followed him.
Some scribes who were Pharisees saw that Jesus was eating with sinners
and tax collectors and said to his disciples,
“Why does he eat with tax collectors and sinners?” 
Jesus heard this and said to them,
“Those who are well do not need a physician, but the sick do.
I did not come to call the righteous but sinners.”
(Mk 2:13-17)

The oldest memory of the Eucharist is the eating and drinking with sinners. As my old homiletics professor used to say about this passage, “If you’re not a ‘sicko,’ you don’t get Jesus.”