In the middle of the Mass, the priest and the servers set up the altar for the Liturgy of the Eucharist. After praying over the bread, the priest or deacon pours some wine into the chalice and then adds a drop of water saying, “By the mystery of this water and wine may we come to share in the divinity of Christ who humbled himself to share in our humanity.”
Mixing water with wine was a common practice in Jesus’ time for the practical reason that wine was very strong. Only barbarians would drink unmixed wine.
For us, though, the mixing of water and wine has a deeper significance. First, we remember that water and blood poured from Jesus’ side when it was pierced on the cross.
The mixing also reminds us, as the prayer says, of the coming together of divinity and humanity, represented by the wine and water. Jesus, by coming among us, joined his divine nature to our human nature - and he invites us to join with him.
Every time we receive communion, the human and divine are joined together as Jesus gives Himself to us.
Mother Teresa once asked a priest to remember her and her sisters every time he put the drop of water in the chalice. It can be helpful for us to think of at every Mass: we are joined intimately with the love of God.---- Fr. Michael