In Fahrenheit 451 by Ray Bradbury, this quote is found at the end of the second section, entitled "The Sieve and the Sand."
Montag has gone to Faber's house, wanting to learn and wanting to change the world. Montag believes that Faber should know a great many people who would take up the cause to stop the burning of books and homes, and end the relentless destruction that is causing people to commit suicide or others to be murdered.
Faber is extremely cautious. He tells Montag that it is hard to know who to trust. Faber sees himself as a coward even as he points out that many people are too afraid to do anything. The change needed is enormous because, as Faber puts it, the whole country is "shot through." They are so busy having fun that the firemen are rarely really needed to enforce the law because people have chosen to stop reading.
Faber advises Montag to go home. Even though the fireman has a new awareness of what is happening in and to his society, Faber discourages Montag as best he can from taking any further steps:
Why waste your final hours racing about your cage denying you're a squirrel.
Montag will not be dissuaded, so he picks up the Bible and starts ripping the pages out. Faber is devastated and finally begs Montag to stop. The fireman agrees but only if Faber will teach him. Faber acquiesces. As they talk Montag points out an interesting irony. While Beatty determinedly leads the firemen to destroy every book they discover, he has obviously read more than his fair share of books. He quotes old and well-known texts all the time. Montag is afraid that Beatty is powerful enough to do or say something to turn Montag back to the man that so recently thought burning books was fun.
Faber explains that people are either builders or burners, and that everyone has some of the burner in him. Then Faber makes a decision. Rather than allowing Montag to go out into the night, he stops him. After a short consideration, the older man opens the bedroom door for Montag to enter. Rather than a bedroom, Montag discovers a workshop where Faber secretly works on electronics. In a cowardly way, Faber admits, he has hid in silence for fear of discovery. In that hidden room, Faber has built an ear bud, something that allows him to speak to someone wearing the bud, and for that person to hear Faber.
Faber explains the only way he was able to afford the setup.
I paid for all this—how? Playing the stock market, of course, the last refuge in the world for the dangerous intellectual out of a job. Well, I played the market and built all this and I've waited. I've waited, trembling, half a lifetime for someone to speak to me.
To finance his electronics workshop, Faber took a chance with the stock market. The ear bud he has made is Montag's first step at fighting back, as he will wear it when he next sees Beatty; Faber will be listening and telling Montag how to respond so Montag can stand up to whatever Beatty has to say to him.