'I worked terribly hard on the problem of the presence of time in art; how to render it perceptible: here I had discovered an element which had to be developed. [...] Gradually, I began suspending certain elements between the plexiglass and the opaque background, both of them striated. It became obvious that their movement could be integrated with optical vibrations: I then began to use these suspended objects which you know; "immaterial curves," rods etc which, through the phenomenon of displacement, disappear, to be perceived merely as vibrations.'
(Jesús Rafael Soto quoted in: Soto: a retrospective exhibition, exh.cat. The Solomon R. Guggenheim Museum, New York 1974, p.16)