Lewis Carroll’s 1885 puzzle book A Tangled Tale bears an anonymous dedication:
Beloved Pupil! Tamed by thee, Addish-, Subtrac-, Multiplica-tion, Division, Fractions, Rule of Three, Attest thy deft manipulation! Then onward! Let the voice of Fame From Age to Age repeat thy story, Till thou has won thyself a name Exceeding even Euclid's glory!
He was thinking of Edith Rix, a child-friend who went on to study mathematics at Cambridge. She might have divined without asking that the dedication was intended for her. How?