Vatican News notes the history of today's feast of the Holy Family:
The Feast of the Holy Family of Jesus, Mary, and Joseph is normally celebrated on the Sunday after Christmas. This feast developed at the beginning of the 19th century in Canada and then spread to the entire Church in 1920. At first, it was celebrated on the Sunday after Epiphany.
It is a Feast that seeks to portray the Holy Family of Nazareth as the “true model of life” (cf. Opening Prayer) from which our families can draw inspiration and know where to find help and comfort.
When Christmas falls on a Sunday, the feast is celebrated December 30. That is, when there is no Sunday within the Octave of Christmas, the Feast of the Holy Family is celebrated on the Sixth Day of the Octave.
Prayer
The hidden life of Nazareth
allows every person
to be in communion with Jesus
along the most ordinary paths of everyday life.
Nazareth is the school
in which we begin to understand
the life of Jesus, that is,
the school of the Gospel...
In the first place, may it teach us silence.
Oh! May an appreciation
of this stupendous and indispensable
atmosphere for the spirit return to us...
May it teach us the way to live in the family.
Nazareth reminds us what the family is,
what communion of love is,
its austere and simple beauty,
its sacred and inviolable character…
Finally, let us learn a lesson of work.
Oh! House of Nazareth,
home of the “Carpenter’s Son”!
Here, we especially want to understand
how to praise the severe but redeeming law
of human labor...
We want to greet workers throughout the world
and show them their great model,
their Divine Brother.
(Saint Pope Paul VI, discourse of 5 January 1964)
The full text of this speech, given during the Pope's pilgrimage to the Holy Land, was printed in the New York Times. See here.