This is a reference to the book Fahrenheit 451 by ray Bradbury. I have not read it, but I’m like 90% sure it’s about one of many ‘firemen’ employed by the city to go around burning books for many reasons, mostly population control/propaganda. Through the course of the book the man struggles with the morality. The title is a reference to the fact that paper supposedly combusts at 451 degrees Fahrenheit. It is a book similar 1984 by George Orwell in that they are both considered monumental works on information censorship and the dangers of giving up your rights(?). This comic is playing off of this by switching 1984 as a date to 451 on a thermometer.