yet when full-grown it is the largest of plants.
It becomes a large bush,
and the birds of the sky come and dwell in its branches.”
-- Mt 13:31-35
"This Kingdom shines out before men in the word, in the works and in the presence of Christ." To welcome Jesus' word is to welcome "the Kingdom itself." The seed and beginning of the Kingdom are the "little flock" of those whom Jesus came to gather around him, the flock whose shepherd he is. They form Jesus' true family. To those whom he thus gathered around him, he taught a new "way of acting" and a prayer of their own.
-- CCC 764
The kingdom of heaven was inaugurated on earth by Christ. "This kingdom shone out before men in the word, in the works and in the presence of Christ" (LG 5). The Church is the seed and beginning of this kingdom. Its keys are entrusted to Peter.
-- CCC 567