He sent them out "two by two"

One thing that we should not gloss over in Sunday's gospel (Luke 10:1-12,16-20) is that the Lord sent out the Seventy "two by two" for their missionary journey. Though never mentioned as an explicit policy in the New Testament, that practice continued as a part of the missionary structure of the early Church. Surely, it was intended by Christ to be a check on individualism and personal authority, to be authoritative and verifiable messengers of truth, to be a reminder of our common life and cooperative work, and to be a means of communion within the body of Christ. I have listed some examples below, but I am sure there are others.

Luke 10:1-2
After this the Lord appointed seventy others and sent them on ahead of him, two by two, into every town and place where he himself was about to go. And he said to them, "The harvest is plentiful, but the laborers are few. Therefore pray earnestly to the Lord of the harvest to send out laborers into his harvest."

Consider also, that Jesus called the first apostles in groups of two: Peter and Andrew (Mt 4:18), then he called James and John (Mt 4:21).

While he was in prison, John sent two of his disciples to inquire about Jesus (Mt 11:2).

Jesus said that when two are in agreement in prayer, their request will be granted (Mt 18:19) and when two are gathered in his name, he would be in their midst (Mt 18:20).

When they needed a donkey for Palm Sunday, Jesus sent out two disciples to obtain one (Mt 21:1).

Jesus sent the twelve out two by two on their missionary journey (Mk 6:7).

Under the direction of the Holy Ghost, the apostles sent Barnabas and Paul on the first great missionary journey of the early Church (Acts 13:2).

Judas Barsabbas and Silas were also sent together (Acts 15:27).

On the next mission trip, Barnabas went with Mark and Paul went with Silas (Acts 15:39-40).

To the Corinthians, Paul describes Titus as "my partner and fellow worker" (2 Cor 8:23).

Paul sent Timothy and Erastus to Macedonia (Acts 19:22).

Paul sent Tychicus and Onesimus to the Colossians (Col 4:7-9).