A Person Is His Name
Rav Rafoel Nachman Kahn told the story of the child Tzemach Tzedek and his Zeidy, and then added a lesson from it: when someone answers to his name being called, that is his essence, that is who he is.
Source: Rav Rafoel Nachman Kahn, in Shemuos Vesippurim, Vol. 1, p. 53