Mark Twain received so many letters from would-be authors that he prepared a standard reply:

Dear Sir or Madam,–Experience has not taught me very much, still it has taught me that it is not wise to criticise a piece of literature, except to an enemy of the person who wrote it; then if you praise it that enemy admires you for your honest manliness, and if you dispraise it he admires you for your sound judgment.

Yours truly,

S.L.C.