'Eventually I found what I was looking for in the conjunction of the vertical and diagonal...this conjunction was the new form. It could be seen as a patch of colour - acting almost like a brush mark. When enlarged, these formal patches became coloured planes that could take up different positions in space'
(B. Riley, quoted in Bridget Riley Flashback, exh. cat., Hayward Gallery, London, 2009, p. 18).
Shadow Rhythm belongs to a series of Bridget Riley's large and intensely colourful paintings that were inspired by a visit to Egypt in the winter of 1979-80. The sensory stimulation provided by this experience resulted in a magnificent new phase in her work which lasted for over a decade. It coincided with a time when Riley began to break up the vertical stripes that had so strongly characterised her previous paintings by introducing opposing diagonal forces. The edge-to-edge contact between stripes had initially allowed Riley to observe the shifting identity of her ever increasingly rich and variegated use of colour through a simple economy of means, but as her palette broadened and intensified after her trip to Egypt, she ultimately found this rigid format to be frustrating. Riley felt the growing complexity of her colour arrangements required a fundamental change in form to more fully explore the spatial advances and recessions afforded by her chosen hues and the new crystalline shapes (or 'zigs' as they are known as in her studio) enabled her to dramatically shatter the picture plane into a myriad of variegated hues.
It is a work that directly responds to Riley's fascination with the optical discoveries of Neo-Impressionist painters like Seurat, and the speed and motion of the Italian Futurists. Through an entirely intuitive process, Riley has tested the particular sequences and rhythms of these colours, harnessing the emerging visual forces within her prescribed framework so they neither congeal in clusters nor break out in a tumultuous manner. The result is a closely woven pictorial space that opens up a sense of depth where once Riley's paintings were made to advance towards the viewer. Yet it is an unstable arena, where the more you look at the composition, the more the rhythms shift before your eye. The syncopated changes of hue and line subvert what would otherwise be a rigid structural order, generating the sense of disturbed equilibrium that forms the essential "subject" of all Riley's work.