This is a marvellous and elegantly arranged retrospective of Kidner's work. Draughtsman and painter. His essential concern has been with the processes of the natural universe which, through the invention of man as scientist, are expressed in mathematical form. Not, it should be emphasised, that he seeks to explain the world as the physicist might; rather, he is interested in revealing something of the mysterious and imponderable nature of space and time. Kidner is keenly intelligent about the researches of the first heroic generations of constructivists; he has continued their work with exacting explorations of his own, scrupulously conducted within a rigorous intellectual framework. His particular contribution (and this goes back to his earliest work on optics and colour) has been variables into regularly intervalled patterns. In this his work directly imitates nature, discovering the infinite range of variations that exists in potentia in any dynamic process. Kidner might be called an enthralled materialist, for whom 'the eye is part of the mind' to borrow a phrase from Leo Steinberg) - and a dynamic part at that: as the eye sees the surface of things, so the play of the mind ma discern and reveal what lies hidden underneath. What is thus made visible is full of surprise and delight. Knowledge increases wonder; but it is wonder on Kidner's part at the creative genius of the human mind as much as at the immensities and mysteries of the space it imaginatively constructs in order to make man's home within it. In the margin of a working drawing he quotes Marat: 'In the vast indifference I make my own order.' For all the strictly systematic procedures that Kidner employs, and the thoroughgoing humanism that informs them, it must finally be said that his work springs to life, beguiling the eye and the mind, as the joyful expression of a sensibility and an intelligence passionately attuned to the natural world, and disposed to praise it.