You have a memory which is as treacherous as the most of the other
attributes of human nature. You sit down and read two hours on an
interesting topic. A friend opens the same subject to you, a day
afterward, in conversation, and you fairly carry him by storm. That is
unfair, for you should say you have been "posting up"--but it shows the
value of a library. By frequent "posting" on whatever you have read, you
become a learned man, which is