Painting by Henry Darger. Collection of Kyoko Lerner.

Sometimes a casual remark may be so charged with a memorable truth that one feels changed by it in a permanent way. It is nearly two decades ago that a friend said to me - the very syntax of his sentence was labored with a private despair that underlay it - "Everything is a distraction from that which makes you tremble."

I don't know what the private vision was that he trembled before, but I remembered his perception as I browsed last week through the "Parallel Visions" show currently at the L.A. County Museum. I have never been so moved by an art exhibition.

Subtitled "Modern Artists and Outsider Art," the show mixes work by such artists-by-profession as Klee and Dubuffet with that by "outsiders" - people working completely outside the borders of the art world, frequently in total isolation, without audience or the expectation of audience and often with no rewards beyond those provided by the work itself. Much of the work, not surprisingly, has an obsessive, even hallucinatory quality.

One "art-historical" aim of the show, according to its catalogue, is to demonstrate the influence of this outsider art on modern art, especially on the work of the professional artists included, some of whom were "discoverers" of outsider art. Having been discovered, a number of the outsiders, it is worth noting, are currently making and selling their art within the "outsider-art" market that is now part of the art world.

I will leave it for others to resolve the confusions inherent in labeling as "outsiders" artists whose work appears in a major museum. The show defines the outsiders as those who sought "neither to please nor to shock a prospective audience" by what they created. That quality of working purely on their own, for goals utterly private, is one of the things that makes the show so moving. Indeed, nearly as compelling as the work itself are some of the artists' biographies:

Henry J. Darger, for example, spent part of his childhood in an institution for the feeble-minded and was employed for most of his adult life as a menial worker at a Chicago hospital. A recluse, essentially invisible so far as society was concerned, he left behind him an extraordinary 15,000-page illustrated saga set in the "realms of the unreal," where horrific battles take place between a nation of child-enslavers and the "Catholic nation of Abbieannia," led by the seven virtuous Vivian sisters. The collaged drawings are both beautiful and shocking, alternating between children's storybook landscapes and gory scenes of mayhem.

Howard Finster, an Alabama preacher with a wife and five kids, had a vision in the 1970s ordering him to "paint sacred artwork," some of which he then used to decorate the elaborate two-acre "plant farm museum" he had previously created. Creator of more than 8,000 visionary works, Finster is an outsider no longer: his resume includes the Library of Congress, an NEA grant, an appearance on the Johnny Carson show and design of an album cover for the Talking Heads.

Ferdinand Cheval, a French postman, spent 33 years building from sandstone an 85-foot long, 40-foot wide "Ideal Palace" of decorated caves, galleries, walkways, grottoes and towers - and then, refused permission to be buried there, spent another eight years constructing his tomb in the local cemetery, where he was interred in 1924.

The show includes 235 works by 74 artists, much of great, even surprising, power. I found myself, for example, standing for much longer than I expected in front of well-known artist Jonathan Borofsky's "Counting from 1 to Infinity," a four-foot high stack of notebook pages on whose top sheet is recorded, in neat columns of successive numbers, the furthest point to which Borofsky got: 2,941,494. My first impulse was to dismiss the object as silly or to deride it as pointless, but then I felt the human terror, mixed with humor and a dash of insanity, behind it. Those thousands of pages too describe an obsessive vision, an insistence on pure focus; they log a kind of spiritual journey into space.

Indeed, this show delineates a raw metaphysics that combines the exhilaration and power of the visions of the work with the anonymity, squalidness and pain in the lives of many of those who made it. The signature of much of the art lies simply in the artists' inescapable compulsion to do it, no matter what, as a kind of compact they made between themselves and some personal god who was their only audience.

For me, the awesome focus in these works is particularly moving. We live in a culture based on distraction. And how easy we find it to be distracted - to lumber between rooms brewing coffee or to turn on the news or to listen to music or to dash off to do invented errands or even to read, instead of sitting still to pierce through to the images that encode our private truths, and then to live faithful to those truths.

Standing before the concentration enshrined in the Parallel Visions show, I roundly accused myself: not only for my chronic restlessness, but for the surrender to cliched thought that goes with it, for the cowardice of my desire to please, for turning away from obsession and inner compulsion - ultimately, for not being serious enough to seek and to cultivate those private visions that constitute that which makes me tremble.

But the show, in addition to generating self-blame, also made me recommit myself to that elusive inner struggle. That may be the greatest praise one can offer to art.