Mormon says the following:
And I, being fifteen years of age and being somewhat of a sober mind, therefore I was visited of the Lord, and tasted and knew of the goodness of Jesus. (Mormon 1:15)
According to Douglas and Robert Clark, there must be something significant concerning the stage of life one goes through at the age of about fourteen or fifteen. Mormon's awakening to spiritual matters at about this age foreshadows a similar awakening at a similar age by the young Joseph Smith (see JS-H 1), who would translate Mormon's record. And the experiences of both these men echo that of their ancient father Abraham, who was fourteen years old (according to the ancient and venerable Book of Jubilees) when he "began understanding" how society had gone astray and consequently "began to pray to the Creator" for guidance. Fifteen is the age specified in Confucian tradition to set one's heart upon learning, and thirteen is the age specified in Jewish tradition for the acceptance of moral responsibility. Similarly, through modern-day prophets, the Lord has specified twelve as the age when worthy young men of his church can receive the Aaronic Priesthood. [E. Douglas Clark and Robert S. Clark, Fathers and Sons in the Book of Mormon, p. 230]