Question: What did visual effects supervisor Ken Ralston compare the feather to?
About the article "Forrest Gump", section "Feather".

Candidate passages:
Kenneth Ralston is a visual effects artist, currently the Visual Effect Supervisor and Creative Head at Sony Pictures Imageworks.
Ralston begun his career at the seminal commercial animation and visual effects company, Cascade Pictures in Hollywood, where he worked on over 150 advertising campaigns in the early 1970s.
In 1976 he was hired at Industrial Light & Magic by Dennis Muren to help George Lucas create the effects for "".
He remained in ILM for 20 years before joining Sony Pictures Imageworks as president.
Ralston is best known for his work in the films of Robert Zemeckis.
Ralston has won five Academy Award for Best Visual Effects, including a Special Achievement Oscar for the visual effects in ', and regular awards for his work on "Forrest Gump", "Death Becomes Her", "Who Framed Roger Rabbit" and "Cocoon".
He was nominated seven more times, for "The Rocketeer", "Jumanji", ', ', ', "Dragonslayer", "Back to the Future Part II" and "Alice in Wonderland". 
Various interpretations have been suggested for the feather present at the opening and conclusion of the film.
Sarah Lyall of "The New York Times" noted several opinions that were made about the feather: "Does the white feather symbolize the unbearable lightness of being?
Forrest Gump's impaired intellect?
The randomness of experience?"
Hanks interpreted the feather as: "Our destiny is only defined by how we deal with the chance elements to our life and that's kind of the embodiment of the feather as it comes in.
Here is this thing that can land anywhere and that it lands at your feet.
It has theological implications that are really huge."
Sally Field compared the feather to fate, saying: "It blows in the wind and just touches down here or there.
Was it planned or was it just perchance?"
Visual effects supervisor Ken Ralston compared the feather to an abstract painting: "It can mean so many things to so many different people.
"The feather is stored in a book titled "Curious George", Forrest's favorite book, which his mother read to him, connecting the scene's present time with his childhood in the 1940s.
The placement of the feather in the book is directly on a picture of the monkey walking on a tightrope.
Whether that was intentional or not, it is very symbolic.
The feather also has a correlation with Jenny's constant obsession with "becoming a bird and flying far far away" due to the abuse (sexual and physical) she endured from her father.
She goes as far in the film as to ask Forrest "if jumped off the bridge, could [she fly?"
 Surname Alexander Ralston, American architect Aron Ralston, American mountain climber Bill Ralston, New Zealand journalist Bob Ralston, American pianist and organist Brian Ralston, American composer Bruce Ralston, Canadian politician Chris Ralston, English rugby union player Dennis Ralston, American tennis player Esther Ralston, American silent film actress Gilbert Ralston, Irish-American writer Gulliver Ralston, British musician Harry Ralston, American screenwriter and director Howard Ralston, American actor Ken Ralston, American visual effects artist James Ralston, Canadian lawyer, soldier, and politician Jobyna Ralston, American silent film actress John Ralston, several people Joseph Ralston, American former Vice Chairman of the Joint Chiefs of Staff Les Ralston, American boxer Norman Ralston, American pilot Robert Ralston, American merchant and philanthropist Samuel M. Ralston, governor of U.S. state of Indiana Steve Ralston, American soccer player Susan Ralston, American businesswoman Vera Ralston, American actress William Chapman Ralston, American businessman and financier William Shedden Ralston, British scholar of Russian Given name Ralston Bowles, American musician Ralston Crawford, American artist Ralston Hill, American stage actor Ralston Westlake, mayor of Columbus, Ohio, USA Fictional Rebel Ralston, character in the Marvel Shared Universe  
The film won the Saturn Award for Best Special Effects and a BAFTA Film Award for Ken Ralston, the special effects supervisor, an Internet-voted 2003 AOL Movies DVD Premiere Award for the trilogy DVDs, a Golden Screen, a Young Artist Award, and the Blimp Awards for Favorite Movie Actor (Michael J.
Fox), and Favorite Movie Actress (Lea Thompson) at the 1990 Kids' Choice Awards.
It was nominated in 1990 for an Academy Award for Visual Effects.
Most visual effects nominations were due to the development of a new computer-controlled camera system, called VistaGlide, which was invented specifically for this film – it enables one actor to play two or even three characters in the same scene while the boundary between the sections of the split screen and the camera itself can be moving.
"Back to the Future Part II" ranks 498 on "Empire" magazine's 2008 list of the 500 greatest movies of all time.