Emil Nolde's awe-struck vision seems to take nature directly, at full tilt: Painting a sunset in the tropics, he apparently looks straight at it and evokes its intensity through untamed, hot color. His paintings of flowers seem no less immediately observed - he sees them closely, and large, as though they were the scaled-up horticulture of some Nordic giant. When he paints the ocean, it heaves with his very experience of it - vast wave-mountains lift into loaded skies, dark with ponderous cloud, brilliant with surges of light: Artist and viewer are thrown into the maelstrom of the seascape.
But this North German painter (1867-1956) knew that there is (as he wrote) ''a vast difference between the worlds of art and nature.'' He also said: ''Nature can be a wonderful help to the artist if he directs her; but she is not herself the artist or his art - that is for him alone.''
Thus the painter does not (of course) believe that the landscape he gazes at to the point of self-transforming vision is actually great patches of light and dark pigment dramatically disposed in a rectangular frame; or rich, strong passages of red paint. He must be conscious of the separateness of the language of painting from the ''language of nature'' in order to find the most powerful and immediate ways of using the first to re-create his experience of the second.
Nevertheless, the transmuting of nature into art is a matter of the most fruitful ambiguity, particularly when the art achieves its own autonomy, as Nolde's does, while still ''expressing nature.''
In his ''Tropical Sun'' of 1914, painted in response to (or in recollection of) sunsets seen on a trip to the Far East (''... orgies of varied color,'' he noted, ''but only for a very few minutes''), there are, at the horizon, and again across the foreground, large, free areas of pure white painting. Although one can read the round patch of crimson paint as the ''sun,'' and the surrounding vermilion as ''sky,'' and though the beetroot-juice purple forms can be seen as ''clouds,'' the green-black mass below as ''trees,'' and other parts of the painting as ''horizon,'' ''water,'' ''reflections,'' still the white passages act, with prime independence, like paint. Their contrasting dazzle seems to be here because the painting as a painting called for them, and wouldn't be whole without them. They might, if one chose to force it, be seen as breakers in the foreground, and as strange cloud formations billowing like steam in the distance. They carry sufficient conviction in their context. But it seems much more convincing that Nolde introduced them in answer to a nonnaturalistic, bold intuition. They are the very point - the undisguised point - where the painting takes on a life, and a potency, of its own, liberated to a degree from ''subject.''
Writing about Nolde's art, Martin Urban has come up with a descriptive phrase: ''the successful audacity of its form.'' This formal daring was certainly encouraged by Nolde's almost 19th-century ''communion with nature,'' his sense of being ''alone in the universe.'' But one never feels that his art is the slave of nature. It never hides the fact that its strengths come from the artist's intense inner life, for which he sought confirmation in the visible world. Just as significantly he found confirmation for its feelings and expression in earlier art: in Gauguin, Van Gogh, and, intriguingly, in Daumier. In the Norwegian painter Munch he must have sensed a like mind.
Nolde belongs squarely to the 20th century in use of nonnaturalistic, defiantly simplified color, and in his capacity to subsume the particularities of drawing under the wholeness of painting: Linear detail is largely lost in ''audacity of form.'' On this hand he can be seen (he briefly saw himself) as a German Expressionist.
On the other hand, however, he retained more than a little of 19th-century Romanticism. One only has to place his seascapes next to the visionary, moon-soaked seascapes of the American painter Albert Pinkham Ryder to realize this period affinity. In this revitalization of earlier attitudes Nolde showed himself more concerned with timeless emotions than with specific traits of his own era - no less than he did when he stated that his best paintings always came ''as a surprise'' to him. ''I painted,'' he said, ''as it were beyond my powers.''