Julian Bell reviews Delacroix and the Rise of Modern Art at the National Gallery, London, on view through May 22, 2016.

Bell observes: "Facts mattered less to Delacroix than the principle that a painting should form a ‘bridge’ from mind to mind. ‘I have told myself a hundred times that painting – that is, the material thing called a painting – is no more than a pretext,’ he wrote in his journal on 18 July 1850, ‘the bridge between the mind of the painter and the mind of the spectator.’ … Delacroix assembled … a compendium of specimens of nature that is equally a compendium of pigments and mediums. The switch from tomato to aubergine becomes a switch from the fattest vermilion to the gauziest suspension of violet-tinged varnish. These colour forays bounce off against one of easel painting’s structural problems, as French tradition defined it – how to unify, how to arrive at cohesive effect through rhythms of highlights and darks."