There are three rules for writing a novel. Unfortunately, no one knows what they are. W. Somerset Maugham

from Wikipedia's entry:

William Somerset Maugham (/ˈmɔːm/ mawm), CH (25 January 1874 – 16 December 1965) was an English playwright, novelist and short story writer. He was among the most popular writers of his era and reputedly the highest paid author during the 1930s.