Charles Scribner IV quotes:

Language is the soul of intellect, and reading is the essential process by which that intellect is cultivated beyond the commonplace experiences of everyday life.

Reading is a means of thinking with another person's mind; it forces you to stretch your own.

Beyond the formative effects of reading on the individuals composing society, the fact that they have read the same books gives them experiences and ideas in common. These constitute a kind of shorthand of ideas which helps make communication quicker and more efficient. That is what we mean when we say figuratively of another person, We speak the same language.