Classical music (music created by musicians who are commonly not classically trained, often from a purely oral tradition). Some composers, like Dvořák and Smetana, have used folk themes to impart a nationalist flavor to their work, while others like Bartók have used specific themes lifted whole from their folk-music origins. Certain staples of classical music are often used commercially (either in advertising or in movie soundtracks). In television commercials, several passages have become clichéd, particularly the opening of Richard Strauss' "Also sprach Zarathustra" (made famous in the film "") and the opening section "O Fortuna" of Carl Orff's "Carmina Burana"; other examples
Interpretations of 2001: A Space Odyssey machines". Kubrick was also confronted with the fact that, during the production of the film, the US and USSR had agreed not to put any nuclear weapons into outer space by signing the Outer Space Treaty. Alexander Walker in a book he wrote with Kubrick's assistance and authorisation, states that Kubrick eventually decided that as nuclear weapons the bombs had "no place at all in the film's thematic development", now being an "orbiting red herring" which would "merely have raised irrelevant questions to suggest this as a reality of the twenty-first century". In the Canadian TV documentary "2001 and Beyond",