老脑筋就像老马；如果你想保持它们的工作状态，就必须锻炼它们。
Old minds are like old horses; you must exercise them if you wish to keep them in working order.
最简单的词语往往承载最重的分量。
The degree of slowness is directly proportional to the intensity of memory. The degree of speed is directly proportional to the intensity of forgetting.