In the earthly relationship to Jesus, Joseph was the earthy shadow of the heavenly father. He watched over the child Jesus and protected him, never leaving him to go his own way.
Fathers are not born, but made. A man does not become a father simply by bringing a child into the world, but by taking up the responsibility to care for that child.
Whenever a man accepts responsibility for the life of another, in some way he becomes a father to that person.
St. Joseph, A Father in the Shadows, Perfect Model for all Fathers, pray for us.