The jumbled old epistles and new letters are piled up on bookshelves or crammed in drawers, some of which have been replied while some haven’t. As Jia Dao wrote in his poem Calling on a Hermit in Vain . “He is here in the mountain. Yet I can’t find his whereabouts through all these thick clouds. ” Picking out the letter that you intend to reply will cost you time and energy several times greater than replying the letter does. Moreover, imagine your friends’ countenance when they get the reply, which is not unexpected delight but reburned lingering anger, and all of your little determination will vanish. Your debt will never be liquidated. Not replying the letters is by no means equal to forgetting friends, as there is absolutely no debtor in the world who will forget his creditor.