This sad state of mind in people who have no religion at all is extremely familiar to the neurologist, and it has no necessary connection with religious practice or religious belief. I have a patient who has been coming to me for many years now from a city in the Middle West; he is a broker, and every time there is a panic in the money market I am almost sure to see him. Whenever he gets very much disturbed over business matters, as is likely to happen in panic times, he develops a very striking _folie du doute_, or doubting mania. He will take a letter to a post box and go back three or four times, first to see if by chance he did not drop it on the way, secondly to be sure that it did not get caught in the slot; then, if the letter is important, he will go back to see if perchance there may not be some bolts or other obstructions at the top of the box that may catch it and delay its collection. I have even known him to wait for some time at the post box to see if the postman might not possibly drop it when he came to collect the mail. But then he does other things just as foolish. Occasionally he will {224} get home from his office and suddenly have the feeling that he forgot to lock his safe. He will go back and then get part way up town when he is overcome by the fear that he may not have locked the door after him as he came out. At times when his _folie du doute_ is at its worst, he has been known to go back three or four times to close windows or for some other trivial reason. When he is in reasonably good condition there is very little of this state of mind manifest, but he can make himself supremely miserable when the obsession is on him.