After searching for three days, Mary and Joseph find the twelve-year-old Jesus sitting in the Temple discussing the law with the learned doctors.Luke 2:42-52
"How is it that you sought Me? Did you not know that I must be about My Father's business?"
This is the answer that Jesus gave to His Mother when, after three days' search she had the joy of finding Him in the Temple. These are the first words coming from the lips of the Word Incarnate to be recorded in the Gospel.
In these words Jesus sums up His whole person, His whole life, His whole mission. They reveal His Divine Sonship; they testify to His supernatural mission. Christ's whole life will only be a clarifying and magnificent exposition of the meaning of these words.
St. Luke goes on to tell us that Mary "did not understand the word that He spoke." But even if Mary did not grasp the full significance of these words, she did not doubt that Jesus was the Son of God. This is why she submitted in silence to that Divine Will which had demanded such a sacrifice of her love. "Mary kept these words of Jesus carefully in her heart." She kept them in her heart, for there was the tabernacle in which she adored the mystery concealed in the words of her Son, waiting until the full light of understanding would be granted her.