I don't have a very good memory. While I have read the Big Book (Alcoholics Anonymous) front to back a number of times, I find it quite difficult to find any particular subject when I need to find it. (yes, I have a Concordance) However, because I have led many meetings and used The Promises as a reading to begin some meetings, I do happen to know where to find that passage.
Having said that ...
Over the weekend, I was doing volunteer service work answering the Intergroup phones at Lambda Center. At 6:25am a young caller asked me if I knew where to find The Promises in the Big Book. First, I asked if he had the book handy. "Yes," he said, "I have it now." I told him to look at the bottom of page 83 and he should find what he's looking for. A moment later, he said, "Thanks a lot!" That was all he wanted. Great. I was so happy I could help him.
An hour later, just before my regular AA meeting, the leader asked me if I would read The Promises at the end of the meeting. "Of course," I told him. I grabbed a book and held it in my lap until the end of that meeting.
I knew exactly where to find what he wanted me to read.