Executed in 1991, 4th Revision of June 23, Study after Cartoon for High Sky exemplifies Bridget Riley’s influential investigations into the optical potential of both colour and form. The painting reflects one of the most radical developments within Riley’s precise and graphic visual dialect: the discovery of the diagonal in 1986. Moving away from her previous works featuring vertical or horizontal coloured lines, Riley’s embrace of the diagonal liberated her from the rigidity and exactitude of the straight line, encouraging her to create paintings of heightened dynamism and vigour. Riley explains:
'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'
The discovery of the diagonal line and the introduction of the lozenge shape further amplified the artist’s already highly personal use of colour. Since her first stripe painting of 1967, colour was the driving force of Bridget Riley’s artistic language and her highly influential trip to Egypt in the early 1980s, marked a further intensification of her investigation in colour. Riley has described the complex methodology of her geometric abstraction:
'Colour is the proper means for what I want to do because it is prone to inflections and inductions existing only through relationship; malleable yet tough and resilient. I do not select colours but rather pairs, triads or groups of colour which taken together act as generators of what be seen through or via the painting. By which I mean that the colours are organised on the canvas so that the eye can travel over the surface in a way parallel to the way it moves over nature. It should feel caressed and soothed, experience frictions and ruptures, glide and drift.'
It is between the dialectical fray of composition and perception that Riley situates her work. As a student, the artist made studies from the works of Georges Seurat (fig. 1), who subscribed to the empiricism of Charles Henry and his theory that mathematical formulation could directly explain aesthetic results. Rejecting Seurat’s technique of pointillism, she instead concentrated on the artist's systematic distillation of colour and his balanced use of complementary hues to delineate light, shade, depth and form. The present work includes echoes of this early exploration of colour, whilst also incorporating the vigorous structural emphasis of her early black and white geometric paintings. Inspired by the ‘all-over’ canvases of Abstract Expressionists like Jackson Pollock, Riley refined their multi-focal vernacular into her own unique artistic language. This is consummately embodied in the pulsating geometrical dynamism of the present work, as Riley combines the logic of early colour theory with a painterly engagement with the surface of the canvas, resulting in a visual sensation that oscillates between the ‘plastic’ neutrality of the repeated form and the optical brilliance of her palette.