Milan. Augustine is thirty-two, not yet converted, and in the habit of calling on the bishop, who is always busy and is never rude about it. Ambrose reads while people wait.

When he was reading, his eyes glided over the pages, and his heart searched out the sense, but his voice and tongue were at rest.

Augustine, Confessions VI.3, c. 397

Augustine cannot account for it and does not pretend to. He offers what he has: perhaps to save a voice that grew hoarse easily; perhaps to avoid being stopped and asked to explain a difficult passage to whoever was listening, which would cost him the little reading time he had. Then he writes that he does not know, and that whatever the reason, it must have been a good one.

Whether silent reading was genuinely rare in the fourth century is argued over by people who have read more of the period than either of us. What is not argued over is that a highly educated man watched it happen and could not immediately say why anyone would do it.

It was written down because it was strange. That record is the only evidence it ever was.