THE THEORY OF THE IMPRESSIONISTS--THE DIVISION OF TONES, COMPLEMENTARY COLOURS, THE STUDY OF ATMOSPHERE--THE IDEAS OF THE IMPRESSIONISTS ON SUBJECT-PICTURES, ON THE BEAUTY OF CHARACTER, ON MODERNITY, AND ON STYLE It should be stated from the outset that there is nothing dogmatic about this explanation of the Impressionist theories, and that it is not the result of a preconceived plan. In art a system is not improvised. A theory is slowly evolved, nearly always unknown to the author, from the discoveries of his sincere instinct, and this theory can only be formulated after years by criticism facing the works. Monet and Manet have worked for a long time without ever thinking that theories would be built upon their paintings. Yet a certain number of considerations will strike the close observer, and I will put these considerations before the reader, after reminding him that spontaneity and feeling are the essentials of all art. [Illustration: DEGAS CARRIAGES AT THE RACES] The Impressionist ideas may be summed up in the following manner:-- In nature no colour exists by itself. The colouring of the objects is a pure illusion: the only creative source of colour is the sunlight which envelopes all things, and reveals them, according to the hours, with infinite modifications. The mystery of matter escapes us; we do not know the exact moment when reality separates itself from unreality. All we know is, that our vision has formed the habit of discerning in the universe two notions: form and colour; but these two notions are inseparable. Only artificially can we distinguish between outline and colour: in nature the distinction does not exist. Light reveals the forms, and, playing upon the different states of matter, the substance of leaves, the grain of stones, the fluidity of air in deep layers, gives them dissimilar colouring. If the light disappears, forms and colours vanish together. We only see colours; everything has a colour, and it is by the perception of the different colour surfaces striking our eyes, that we conceive the forms, _i.e._ the outlines of these colours. The idea of distance, of perspective, of volume is given us by darker or lighter colours: this idea is what is called in painting the sense of values. A value is the degree of dark or light intensity, which permits our eyes to comprehend that one object is further or nearer than another. And as painting is not and cannot be the _imitation_ of nature, but merely her artificial interpretation, since it only has at its disposal two out of three dimensions, the values are the only means that remain for expressing depth on a flat surface.