“The Riddle of Lumen” presents an evenly paced sequence of images, which seem to follow an elusive logic. As in “Zorns Lemma” the viewer is called upon to recognize or invent a principle of association linking each shot with its predecessor. However, here the connection is nonverbal. A similarity, or an antithesis, of color, shape, saturation, movement, composition, or depth links one shot to another. A telling negative moment occurs in the film when we see a child studying a didactic reader in which simply represented objects are coupled with their monosyllabic names in alphabetical order. –P. Adams Sitney. Preserved by the Academy Film Archive in 2007.