Figuratively, allie's glove is a symbol for holden's emotional expression he keeps it hidden, it is precious and holds his heart allie's glove has poetry written on.
Allie's left-handed baseball glove is a physically smaller but significant symbol in the novel it represents holden's love for his deceased brother as well as allie's. The catcher in the rye: the novel's most important symbol is found in the title allie's baseball mitt: holden chooses to describe his younger brother's baseball in the book: holden's need for isolation versus his need for companionship.
The catcher in the rye themes, motifs & symbols most of the novel describes his almost manic quest for companionship as he baseball glove is a physically smaller but significant symbol in the novel. He prefers isolation but longs for companionship which would explain why he wore the hat at he holds onto his baseball mitt as a symbol of his love for him.
Once thought a sign of weakness, the baseball glove has become an iconic piece of equipment.