This "original nuclear family" symbolized the Holy Trinity to many early Christian believers. They solidified the family unit with such deep spiritual significance that the Holy Family eventually became an integral part of Roman Catholic religious dogma.
The Scriptures and many apocryphal works were passed down either by word of mouth or through song, and later in works of art. The symbolism of the Child Jesus in art reached its apex during the Renaissance: the holy family was a central theme in the works of Leonardo Da Vinci and many other masters.
Simeon would not see death before he had seen the Lord's Christ
25 Now there was a man in Jerusalem, whose name was Simeon, and this man was righteous and devout, waiting for the consolation of Israel, and the Holy Spirit was upon him. 26 And it had been revealed to him by the Holy Spirit that he would not see death before he had seen the Lord’s Christ. 27 And he came in the Spirit into the temple, and when the parents brought in the child Jesus, to do for him according to the custom of the Law, 28 he took him up in his arms and blessed God and said 29 "Lord, now you are letting your servant depart in peace, according to your word;30 for my eyes have seen your salvation 31 that you have prepared in the presence of all peoples, 32 a light for revelation to the Gentiles, and for glory to your people Israel.". –Luke 2:25-32