In A History of Reading, the Canadian novelist and essayist Alberto Manguel describes a remarkable transformation of human consciousness, which took place around the 10th century A.D.: the advent of silent reading. Human beings have been reading for thousands of years, but in antiquity, the normal thing was to read aloud. When Augustine (the future St. Augustine) went to see his teacher, Ambrose, in Milan, in 384 A.D., he was stunned to see him looking at a book and not saying anything. With the advent of silent reading, Manguel writes,
... the reader was at last able to establish an unrestricted relationship with the book and the words. The words no longer needed to occupy the time required to pronounce them. They could exist in interior space, rushing on or barely begun, fully deciphered or only half-said, while the reader’s thoughts inspected them at leisure, drawing new notions from them, allowing comparisons from memory or from other books left open for simultaneous perusal.
To read silently is to free your mind to reflect, to remember, to question and compare. The cognitive scientist Maryanne Wolf calls this freedom “the secret gift of time to think”: When the reading brain becomes able to process written symbols automatically, the thinking brain, the I, has time to go beyond those symbols, to develop itself and the culture in which it lives.