"Every day of his life Mr. Lowell had had the feeling that he was being watched, and today was to prove no different. Sooner or later he would have to get those prescription glasses fixed so he might spot who was watching him. His optician had made a mistake and read +3 as -3, but Mr. Lowell's reticent nature had thus far prevented him from pointing this out, or getting them corrected. Recently, however, his old optician had passed away, and so he had felt that it would not be immodest to have this change done, in the guise of wanting a new pair of frames. What he did not know was that his old optician had left detailed notes on every transaction, and thus his successor greeted him with an exact recollection of the prescription used, resulting in another pair of glasses with the same problem. Pondering this state of affairs, he was able to ignore the little voice telling him he was being watched yet again."