If you want to convey fact, this can only ever be done through a form of distortion. You must distort to transform what is called appearance into image.-- Francis Bacon
The documentary is The Art of Francis Bacon (2007), and the bulk of the running time is filled with views of Bacon's paintings accompanied by the actor Derek Jacobi reading Bacon's own words.
Perhaps like me, you'll be struck by the musical score. It is original music composed by brothers Adam and Jez Burns, and suits the mood perfectly.
I enjoyed this one very much. Watch it here at Documentary Heaven: The Art of Francis Bacon.