How did Granger and the other men carry their books?

In Fahrenheit 451, Granger and the other men and women at the camp of intellectual outlaws carry their books by not carrying them at all; they memorize the texts in order to avoid physically possessing them. By memorizing the texts, they essentially embody, or contain, the books, hoarding the words and information in their own heads. Their plan is to collect enough "criminals" who are willing to memorize the most important texts and consequently build a sort of library of people.
Granger memorizes Republic by Plato. Montag ends up with the assignment of memorizing the books of Ecclesiastes and Revelation from the Christian Bible.
Granger introduces the other men and women at the camp:

Here we all are, Montag. Aristophanes and Mahatma Gandhi and Gautama Buddha and Confucius and Thomas Love Peacock and Thomas Jefferson and Mr. Lincoln, if you please. We are also Matthew, Mark, Luke, and John.

The idea of memorizing the books rather than physically possessing shows the importance of one of the themes of Fahrenheit 451: the ideas and words of books are greater than the physical books themselves. Fahrenheit 451, for instance, contains themes and ideas bigger than the novel itself. It challenges society and the outrageous idea of banning texts.