An Excerpt from St. Ambrose
On the Gospel
And when he was twelve years old. The public teaching of the Lord had, as we read, its beginning from His twelfth year, for herein should be foreshadowed the number of those announcing the faith that was to be preached. Nor was it that He was headlessly unmindful of His parents according to the flesh, Who in the flesh was filled with grace and wisdom, that He was found in the Temple after three days, but for a sign that He was believed dead would present Himself to our faith, risen in heavenly glory and divine honor after the three days of that triumphal passion.
How is it that you sought me? Did you not know that I must be about my Father’s business? There are two generations in Christ: the one is Paternal, the other maternal; that which is Paternal is more divine (divinior), the maternal that whereby He has stooped to our need and benefit. And therefore what was accomplished in a manner above nature, above age, above what was usual, must not be ascribed to His human excellence, but must be referred to the power of His divinity.
Elsewhere His mother pleads with Him for a miracle: here she requires of Him a reason, since she still looks to the things that are human. But while here He is described as being but twelve years old, there He is spoken of as having disciples. See how the mother has learned to know her Son, so that she seeks a miracle from Him now in His full strength, who was astonished at this wonder in His boyhood.