Etcher, water colorist, painter in oils, Marin is a significant figure in modern art. Here is a full scale appreciation and interpretation of him as ""impressionist, abstractionist, realist?"" -- but assuredly one of the first of American extremists. This is a story of man and artist, although his characteristic shy reserve lends a certain restraint to his personal history. A boyhood in Jersey; the inevitable pilgrimage to Europe in 1905, where he stayed five years and where his style crystalized; his first shows, under the aegis of Stieglitz who retained a protective guardianship over Marin for several decades; the years of restlessness, little recognition; the Maine paintings- later New Mexico; and finally in the '30's recognition and fame. The plainness, the simplicity of the man engages sympathy, but fails to capture imagination to those not already intrigued by his work. The reproductions of his work in color have caught the essential quality of his painting.