When Montag and his team of fireman arrive at a woman's house to burn it, she greets him with a quotation: "Master Ridley, we shall this day light such a candle, by God's grace, in England, as I trust shall never be put out.
The quotation is from Hugh Latimer, who lived from 1487-1555. Latimer was an English clergyman who developed religious ideas that were considered heretical by the Church of England establishment under the leadership of Queen Mary.
In 1555, Latimer was sentenced to death, together with a colleague named Nicholas Ridley. Just before being killed, Latimer addressed Ridley and uttered the words quoted above. He seems to have meant that his sacrifice for his ideals will eventually help those ideas to become accepted.
This would also seem to be the intent of the woman in Fahrenheit 451. By burning herself together with her books, the woman hopes to demonstrate and publicize her resistance to the firemen.
When the firemen arrive at her house, the woman recites the following quote:
Play the man, Master Ridley; we shall this day light such a candle, by God's grace, in England, as I trust shall never be put out.
This quote was spoken by Hugh Latimer, a Protestant who was burned at the stake for heresy in 1555. Allegedly, Latimer uttered this phrase to his fellow heretic, Nicholas Ridley, at the moment of their execution. These men were labeled heretics because of their Protestant beliefs during the reign of Queen Mary, a staunch Catholic.
By alluding to Latimer and Ridley, then, this woman implies that she, too, is a heretic. Although this is not a question of religion, she is about to lose her life for something that she strongly believes in: books. Moreover, by speaking this quote, she shows her defiance in the face of censorship: she is ready and willing to die for her love of books and learning, just as Latimer and Ridley died for their beliefs.
In addition, this quote also demonstrates hope. Latimer believed that his death would light a candle that might never be put out. By repeating this phrase, the woman expresses the hope that somebody will follow her example and realize the dangers of censorship. As such, this quote foreshadows Montag's own (impending) rebellion against the state's control over books.
Yes as the other post said, that is the reference. The line implies it is said by a martyr, but also in this particular case, both "sayers" were 'burned" at the stake, so to speak.