What is central message of the 1971 film Duel?

The central message of the 1971 film "Duel" revolves around the theme of man versus machine and the psychological effects of fear and paranoia. It highlights how a seemingly mundane encounter can escalate into a life-and-death struggle, reflecting the fragility of human existence in the face of relentless and impersonal forces. The film also explores the concept of isolation, as the protagonist confronts his adversary alone on a desolate highway, emphasizing the struggle for survival against overwhelming odds.