Though a rather vague term, as it's difficult to date exactly when the backlash against Impressionism took place, Post-Impressionism represents in many ways a return to more formal concepts of painting - in composition, in attitudes to subject and in drawing.

Paul Cézanne (1839-1906), for one, associated only very briefly with the Impressionists and spent most of his working life in relative isolation, obsessed with rendering, as objectively as possible, the essence of form. He saw objects as basic shapes - cylinders, cones, etc - and tried to give the painting a unity of texture that would force the spectator to view it not so much as representation of the world but rather as an entity in its own right, as an object as real and dense as the objects surrounding it. It was this striving for pictorial unity that led him to cover the entire surface of the picture with small, equal brush strokes which made no distinction between the textures of a tree, a house or the sky.

The detached, unemotional way in which Cézanne painted was not unlike that of the seventeenth-century artist Poussin, and he found a contemporary parallel in the work of Georges Seurat (1859-91). Seurat was fascinated by current theories of light and colour, and he attempted to apply them in a systematic way, creating different shades and tones by placing tiny spots of pure colour side by side, which the eye could in turn fuse together to see the colours mixed out of their various components. This pointillist technique also had the effect of giving monumentality to everyday scenes of contemporary life.

While Cézanne, Seurat and, for that matter, the Impressionists, sought to represent the outside world objectively, several other artists - the Symbolists - were seeking a different kind of truth, through the subjective experience of fantasy and dreams. Gustave Moreau (1840-98) represented, in complex paintings, the intricate worlds of the romantic fairy tale, his visions expressed in a wealth of naturalistic details. The style of Puvis de Chavannes (1824-98) was more restrained and more obviously concerned with design and the decorative. And a third artist, Odilon Redon (1840-1916), produced some weird and visionary graphic work that especially intrigued Symbolist writers; his less frequent works in colour belong to the later part of his life.

The subjectivity of the Symbolists was of great importance to the art of Paul Gauguin (1848-1903). He started life as a stockbroker who collected Impressionist paintings, a Sunday artist who gave up his job in 1883 to dedicate himself to painting.

During his stay in Pont-Aven in Brittany, Gauguin worked with a number of artists who called themselves the Nabis , among them Paul Serusier and Émile Bernard . He began exploring ways of expressing concepts and emotions by means of large areas of colour and powerful forms, and developed a unique style that was heavily indebted to his knowledge of Japanese prints and of the tapestries and stained glass of medieval art. His search for the primitive expression of primitive emotions took him eventually to the South Sea islands and Tahiti, where he found some of his most inspiring subjects and painted some of his best-known canvases.

A similar derivation from Symbolist art and a wish to exteriorize emotions and ideas by means of strong colours, lines and shapes underlies the work of Vincent Van Gogh (1853-90), a Dutch painter who came to live in France. Like Gauguin, with whom he had an admiring but stormy friendship, Van Gogh started painting relatively late in life, lightening his palette in Paris under the influence of the Impressionists, and then heading south to Arles where, struck by the harshness of the Mediterranean light, he turned out such frantic expressionistic pieces as The Reaper and Wheatfield with Crows . In all his later pictures the paint is thickly laid on in increasingly abstract patterns that follow the shapes and tortuous paths of his deep inner melancholy.

Both Gauguin and Van Gogh saw objects and colours as means of representing ideas and subjective feelings. Édouard Vuillard (1868-1940) and Pierre Bonnard (1867-1947) combined this with Cézanne's insistence on unifying the surface and texture of the picture. The result was, in both cases, paintings of often intimate scenes in which figures and objects are blended together in a series of complicated patterns. In some of Vuillard's works, people dressed in checked material, for example, merge into the flowered wallpaper behind them, and in the paintings of Bonnard, the glowing design of the canvas itself is as important as what it's trying to represent.