Watched this yet again in preparation for Q&A with William Friedkin at the London Film School. What impressed me this time was the use of sound bridges (pre-fades to use the technical jargon) as one scene transitions into the next. Witness the genius of the cut from the close-up shots of Karras performing the Eucharist and speaking about "the mystery of faith." to Reagan (in Mercedes McCambridge's raspy, deep voice) saying, "What a lovely day for a exorcism."