Discussing Heron's works from the mid 1960s, Mel Gooding (Patrick Heron, London, 1994, p. 185) comments, 'An emphasis on the structure of the paintings of the mid-1960s, and on its expressive relation to the pictorial exploration of the possibilities of colour should not be taken to indicate any didactic purpose on Heron's part. His work at this time plays subversively with those geometric forms that have since Pythagorus been seen as signs of an ideal universe parallel to our own. Heron is resolutely materialist, but his philosophy is embodied in his art in terms of exemplification and expressive form, and linked in his mind, significantly, with the physical flatness of the canvas as a reality whose truth must be admitted even when a painter is interested in the representation of figures and objects in illusionistic space. Hence his reverence for Bonnard, Braque and Matisse, and his comparative reservations about Picasso. There is an underlying coherence in this: the joyfully anarchic pictures of the mid-1960s, whose wobbly shapes are like parodic versions of Platonic forms, curvilinear and kinetic rather than straight and still, are indeed compositions of that 'abstract music of interacting form-colour' that he wrote of in his 1947 essay on Bonnard. 'Unlike Ben Nicholson I have never in my life drawn a straight line or a purely circular circle or disc,' he was to write in 1973. 'To my eye, at least, an absolutely straight line or colour edge, and a pure arc or circle, both seem destructive of the flatness of the picture surface: both seem to me to rise up off it, or to sink back too deeply into it'.