Glory
Librarians like to help people. Gratitude for a job well done is its own glory, and it's what makes the world go round in that dusty and musty world of library science. Anyone whose research project you rescued or whose life was changed by a book you scouted and recommended will remember you forever...or at least for a little while.
And a lot of times, glory's just a little wry smile on the face of a young kid who, because of you, finally got why George was so curious.