Audiobook Dictation: “The exercise consists of half a…”

The exercise consists of half a chapter of Thucydides. I had to read it over carefully, as the text must be absolutely correct. I had, however, promised to take tea in a friend's rooms, so I left the proof upon my desk. I was absent rather more than an hour. As I approached my outer door, I was amazed to see a key in it. For an instant I imagined that I had left my own there, but on feeling in my pocket I found that it was all right.