I want to know who authored the phrase, "only cream and bastards rise"?

This vivid phrase is attributed to author William Goldman. It appears
in his screenplay for the 1966 film "Harper," in which Paul Newman, as
the private investigator Lew Harper, speaks the line. The movie was
based upon Ross Macdonald's novel "The Moving Target" (in which the
lead character's surname is Archer, not Harper), but the "cream and
bastards" line is Goldman's.

"The bottom is loaded with nice people, Albert. Only cream and
bastards rise."

Internet Movie Database
http://us.imdb.com/title/tt0060490/quotes

"Private eye Harper (Paul Newman) to Albert Graves (Arthur Hill) in
Harper (1966): 'The bottom is loaded with nice people, Albert. Only
cream and bastards rise."

Sex Lexicon: Quotes
http://216.58.107.91/CFQuotes/PEOPLE.html

"Actually 'Only cream and bastards rise.' wrote William Goldman."

MUD Developers' List Archive
http://www.kanga.nu/archives/MUD-Dev-L/2001Q4/msg00650.php

William Goldman has created many other memorable phases; his
screenplays for such classics as "Butch Cassidy and the Sundance Kid,"
"Marathon Man," and "The Princess Bride" are gold mines for pithy
sayings such as "I have vision, and the rest of the world wears
bifocals," "Is it safe?" and "You rush a miracle man, you get rotten
miracles."

Google search strategy:

Google Web Search: "cream and bastards"
://www.google.com/search?hl=en&ie=UTF-8&oe=UTF-8&q=%22cream+and+bastards

Thanks for a fun question about one of my favorite authors! If
anything is unclear, or if a link does not function, please request
clarification; I'll gladly offer further assistance before you rate my
answer.

Best regards,
pinkfreud

In a similar vein, I have also heard "s**t floats", although I have no
idea of the source.

jeremymiles-ga

Thank you very much for the five-star rating and the nice tip!

~pinkfreud