Essentially a single image in continual metamorphosis, Circle conveys a sense of metaphysical reality. Mounting a camera to overlook a portion of his backyard, Jack Chambers exposed four seconds of film at 10am every day for a year. This central section of the film is bracketed by a prologue and epilogue. The aperture and camera position were never varied; as a result, the only "action" in the film is natural – the daily changes in light and colour become the protagonists, free from any intervention by the filmmaker.

Light also serves as the film’s subject – light as contained within a space, and as the arbiter of change within that space. The light impacts so radically upon the physical elements of the setting that each shot seems to be in a different location. Aptly described as "romantic," Circle was characterized by one critic as "one extended haiku, or 365 four-second haikus." Comparable to Michael Snow’s Wavelength (1967), it is a key work in the Canadian experimental tradition.