Read the extract and answer the questions that follow.
But meantime, a thought – a rather painful thought – has begun to come in to my mind at intervals. It is this. If Todd owes a dollar and has forgotten it, it is possible – indeed it is theoretically probable – that there must be men to whom I owe a dollar which I have forgotten. There may be a list of them. The more I think of it the less I like it, because I am quite sure that If I had once forgotten a dollar, I should never pay it, on this side of the grave.
What painful thought comes to the narrator’s mind as he thinks about his lost dollar?