Rabbi Akiva is remembered as the greatest student of Torah in his generation — but he did not begin that way. The Exempla preserves a small story about the door through which he entered the study hall.
Akiva was walking once through an open field when he came upon an unclaimed corpse — a man who had died without family and been left on the ground. The law that governs such a case is called met mitzvah, "the commanded dead": whoever finds an abandoned body is obligated to bury it, even if he is a High Priest ritually forbidden to touch the dead. It is the one obligation that trumps almost every other.
Akiva stopped, lifted the body with his own hands, carried it, and buried it. The field's silence became the shovel's rhythm and then the stillness of closed earth.
But afterward, when he told his story to a teacher, the teacher rebuked him. "You should not have carried the body all that way. You should have buried it where you found it." Akiva realized he had done a mitzvah imperfectly. He had been ignorant of a detail of the law that would have been second nature to any student.
From that moment, the tradition says, the fire lit. Akiva went to the beit midrash and began learning, starting at the age of forty with the alphabet itself, and did not stop until he had become the teacher of the entire generation — all because the dust of one unburied man had shown him what he did not know.
(From The Exempla of the Rabbis, Moses Gaster, 1924, no. 97.)