link to essay on Nostalghia, and ideas of Bergson and Deleuze
"...the film is structured around the protagonist’s internal and immeasurable personal time. This oneiric structure creates a continual sense of temporal instability throughout the film that is exemplified through smooth, seamless transitions between the protagonist’s different states of consciousness and temporality. Most importantly, Tarkovsky employs a long-take aesthetic to express constant durational shifts between the “exterior” world and Gorchakov’s “inner” world." –Michael Vesia, "Transcendental Images of Time and Memory"