What does the old woman do that leaves the fireman speechless?

In Ray Bradbury's "Fahrenheit 451," the old woman defiantly chooses to die with her books rather than abandon them when the firemen arrive to burn her collection. She lights a match and ignites the books, declaring her love for them and expressing her willingness to sacrifice her life for knowledge and literature. This act of courage and conviction leaves the fireman, Montag, speechless and deeply unsettled, prompting him to question the society he serves and his own beliefs.