The phrase in question is a metaphor. A metaphor is a comparison that does not use the words "like" or "as." In this instance, Faber is comparing a book to a living, breathing organism that has pores to let air in and out.

Faber goes onto to describe books as having details that can be put under a microscope and examined. The more details a book has, the better he says. Great books use many details to "touch" life.

Faber goes on to extend the pores metaphor, saying books "show the pores in the face of life." They are hated and banned because people don't want to see life depicted in all its uncomfortable reality. Instead, they want the blandness of "wax moon faces" that won't challenge them to think.

Bradbury is a lyrical writer who loves to use visual imagery and metaphor.

The literary technique (or device), regarding the quote in question from Ray Bradbury's Fahrenheit 451, is a hyperbole. A hyperbole is an exaggeration used for emphasis. 

In the quote, Professor Faber is discussing the importance of books (as receptacles of things one wishes not to forget). In this section, Faber is using imagery and symbolism to explain the importance of books. The book does not actually have pores (this is not meant to be taken literally). Instead, it is meant to be taken figuratively. Pores breathe. Pores possess texture. Therefore, the book (figuratively) is able to breathe. The book has a quality of being something which is living and can be felt. As the quote goes on, the image of the book existing as a living breathing being continues.