Focus on Christ in the House of His Parents and explain the Subject.
The painting depicts the young Jesus assisting Joseph in his workshop. Joseph is making a door, which is laid upon his carpentry work-table. Jesus has cut his hand on an exposed nail, symbolizing the stigmata and foreshadowing Jesus's crucifixion. Some of the blood has fallen onto his foot. As Jesus's grandmother, Anne, removes the nail with a pair of pincers, his concerned mother, Mary, offers her cheek for a kiss. Joseph examines Jesus's wounded hand. A young boy, who would later be known as John the Baptist, brings in water to wash the wound, prefiguring his later baptism of Christ. An assistant of Joseph, who represents Jesus's future Apostles, observes these events. 
In the background of the painting various objects are used to further symbolize the theological significance of the subject. A ladder, referring to Jacob's Ladder, leans against the back wall, and a dove which represents the Holy Spirit rests on it. Other carpentry implements refer to the Holy Trinity. Millais likely used Albrecht Dürer's print Melancholia I as a source for this imagery, along with quattrocento works. The sheep in the sheepfold seen through the door represent the future Christian flock.It has been suggested that Millais was influenced by John Rogers Herbert's painting Our Saviour Subject to His Parents at Nazareth. He may also have drawn on a painting depicting Jesus helping Joseph in his workshop, which at the time was attributed to Annibale Carracci.
Annibale Carracci dove Jesus Holy Spirit stigmata Mary crucifixion Melancholia I quattrocento John the Baptist Anne Trinity Holy Trinity Apostles Jacob's Ladder sheepfold John Rogers Herbert Albrecht Dürer