From the Treasury of Daily Prayer:

John the Baptist and Jesus, the two great figures of salvation history, now come together in the visit to Elizabeth by the Virgin Mary (Luke 1:39-45), both of whom conceived their children under miraculous circumstances. Thus John is brought into the presence of Jesus while they are still in their mothers’ wombs. This presence of the Lord causes a response by the child John as he leaps in Elizabeth’s womb. John’s response to the presence of Jesus, the Messiah, foreshadows John’s own role as forerunner. Already now, a new creation is beginning, and a baby still in the womb hails the new creation’s inception. Foreshadowed in John’s leap are the miracles of Jesus, who will cause all creation to leap at His presence: “The blind receive their sight, the lame walk, lepers are cleansed, the deaf hear, the dead are raised up, the poor have good news preached to them” (Luke 7:22). The incarnate presence of the Messiah also evokes a response from Elizabeth, who proclaims Mary’s blessedness. Mary’s Magnificat (Luke 1:46-55) provides the theological significance of this meeting as Mary sums up her place in salvation history. Mary’s song is a hymn to God for His gracious gifts to the least in this world, whom He has lifted up out of lowliness solely because of His grace and mercy.