The art-quest, documented and validated. Weschler's interview profile of California abstract-expressionist/minimalist/space-manipulator Robert Irwin, part of which appeared in The New Yorker, exhibits all the failings of that genre: three-quarters consists of Irwin talking (supplemented by his mother, and a few associates); not only does Weschler scant independent reporting, his occasional observations are mostly paraphrase; the art-world context is so meager that one might not realize, for instance, that experiments in perceptual abstraction were pervasive in the Sixties. And though one of Weschler's points is that this way-out artist is a regular guy, he pretentiously titles his four sections Lifesource, Narrows, Delta, Oceanic. None of this, however, prevents the book from succeeding as a recapitulation of Irwin's career--his passage from absorption, as a suburban L.A. teenager, in remaking cars (at 53 or so, he still bristles at a friend's unthinking defacement of ""my twenty coats of ruby-red maroon""), to his present involvement in remaking public spaces: ""maximum transformation with minimum alteration"" (and little angst). Talking art, Irwin is direct, plainspoken, precise: by now, he has intellectualized a process that was originally intuitive--which he wishes to convey to others, to rev up their aesthetic perception. Explaining his break with abstract expressionism, he speaks of ""the actual physicality of a post-cubist painting""--the spatial contradiction of overlapping strokes of color; the need for ""interpenetration between figure and ground."" Thus his own experiments: first, working on a small scale, replacing gesture with texture, creating an intimate, hand-held object (finished inside and out, like his cars); then, trying in turn a web of lines (""Those push-pull intersections were dramatic, but they weren't really necessary""), straight lines on a single colored ground, two horizontal lines on a ground of the same color. ""And it was soon thereafter, when I moved one of those lines that eighth of an inch, that I suddenly realized that that gesture changed everything in the field."" There followed the elimination of surface imagery, ""the marriage between painting and environment."" Interesting, ponderable sidelights emerge: Irwin as a California artist--and a racetrack handicapper (source, often, of his income); his practice of ""being available in response""--of going anywhere to talk or create, gratis (""the one thing I can contribute socially at this point""). Lucid and personable--with a particular appeal to the young or the perplexed.