He said it best with four corners and found objects

For decades in the mid-20th century, the American assemblage artist Joseph Cornell languished in relative obscurity, thought to be a New York suburban eccentric who tinkered with art in his spare time. His quirky, highly original box constructions appeared mainly to be of interest to himself, his family, and the Manhattan avant-garde.

But since Cornell's death in 1972, his reputation has gained tremendous ground, with a growing number of books, including a 1997 biography, dedicated to his life and work.

Now, a major retrospective at the Smithsonian Museum of American Art in Washington – the first Cornell retrospective in more than 25 years – reveals him as an artist worthy of the contemporary mainstream, the creator of a unique aesthetic universe that resonates with the American public.

"Joseph Cornell: Navigating the Imagination" presents 203 examples of his work, 30 being shown in public for the first time. Cornell boxes, dossiers, films, and collages present an insight into the mind of an idiosyncratic artist who was resolutely himself, following his own intuitive path despite the personal cost.

The self-taught Cornell didn't really draw, sculpt, or paint. His was an art of choosing, placing, and juxtaposing that began with collage and grew into the three-dimensional medium that was to define him: arranging iconic objects in a box to form a picture or statement, a visual poem without words.

Inspired, in part, by the dioramas he liked to visit in the Museum of Natural History in Manhattan, Cornell's boxes are worlds unto themselves. They vary in mood – from the comic to the melancholic, the obscure to the sublime.

In providing the content of his boxes, Cornell became a master of what to do with what modern art critics now term the "found object" – the ephemera of everyday life. He was particularly fascinated by shells, feathers, bracelets, watches, toy balls, clay pipes, old cutout pictures, and antique charts.

By developing his art of arrangement, he became a founder of the school that has led to the contemporary trend of room-size installation art – a style that amounts to the Cornell box writ large.

In his collages and boxes, Cornell favored an arresting kind of juxtaposition that owes its roots to Surrealism.

"Cornell found that certain everyday items, particularly when placed in unaccustomed juxtaposition, seem ... to intimate a realm that is unchanging and perfect," wrote art critic Richard Vine in the 2003 book "Joseph Cornell: Shadowplay ... Eterniday."

As his work progressed, Cornell chose to explore and develop particular themes. These include his highly regarded "Aviary" boxes, mostly dating from 1949 to 1954; his Soap Bubble Sets (beginning in 1936); and his Hotel series (dating from 1950).

"Untitled" (Cockatoo With Watch Faces, 1949) – pictured here – is an example from the Aviary series built around Cornell's fascination with domesticated birds. In this box, he surrounds the white cockatoo with watch faces, emblems of passing time.

In "Untitled" (Soap Bubble Set, 1936), also pictured here, Cornell explores the significance of an object that, in a sense, is not an object and is certainly impossible to preserve: the evanescent soap bubble. He gives us paraphernalia that create, surround, or suggest the bubble – a clay pipe, a blue egg, a roundish sculpture of a child's head, a map of the moon – but the bubble itself remains illusive.

The life of Joseph Cornell has become as fascinating as his art. Unlike many artists in the modern canon, Cornell was remarkable not for his life's outrageousness and iconoclastic quality, but for his quietness, dedication to family, and religious devotion. In homage to Cornell's lifestyle, the exhibit includes a display of the contents of the famous basement studio where he stored his cornucopia of objects.

Some Cornell skeptics want a definitive assessment of what his quizzical art means. But many critics agree that what is intriguing about Cornell is the ambiguity of his work, its stubborn silence. It can be appreciated on the level of appearance and design, texture, shape, and form. Or the boxes can be viewed metaphorically – the objects in them as symbols of an ever-shifting and expanding set of meanings.

In his work, Cornell set out to do nothing less than rearrange the world, taking objects of life and ordering them into art. What is on view in this retrospective is the result – the mind and sensibility of an American original whose work is modern yet nostalgic, whimsical yet profound.

• 'Joseph Cornell: Navigating the Imagination' is at the Smithsonian American Art Museum in Washington through Feb. 19. It then travels to the Peabody Essex Museum in Salem, Mass., April 28-Aug.19, and to the San Francisco Museum of Modern Art, Oct. 6, 2007 through Jan. 6, 2008.