Let me recommend you to keep a record of Letters Received and Sent. I have kept one for many years, and have found it of the greatest possible service, in many ways: it secures my answering Letters, however long they have to wait; it enables me to refer, for my own guidance, to the details of previous correspondence, though the actual Letters may have been destroyed long ago; and, most valuable feature of all, if any difficulty arises, years afterwards, in connection with a half-forgotten correspondence, it enables me to say, with confidence, "I did not tell you that he was 'an invaluable servant in