Bringhurst’s What Is Reading for? spends just over thirty pages addressing the question in its title, but it’s this single sentence answer that most struck me:

Why? For the same reason we walk, talk, and make love. Because that’s how the species transmits itself from yesterday to tomorrow.

Bringhurst, What Is Reading for?, page 32

Echoes of Eisenstein’s “typographical fixity.” As Bringhurst would no doubt suggest, we may lose some of that with the transition from paper to pixels. But only if we choose to.