One of the most interesting, influential makers of contemporary art is having shows at both the Phillips Collection here in Washington and the Metropolitan Museum in New York. His photos hit on all the crucial features of today's most valued work: They are more concerned with what they show than with how good they look; they come in series, riffing on a simple concept and its complex permutations; they often have political and social implications, though they also work against a final take on things.

But you won't see this artist at art-world parties, or at the frequent unveilings of his work. August Sander died in 1964, and many of his most influential images were made between the two world wars.

Sander, born in Germany in 1876, is best known for a huge, never-finished inventory of photographic portraits called "People of the 20th Century." A touring show now at the Metropolitan has assembled 149 of these portraits into a comprehensive sampling from the project, which Sander had imagined might have as many as 600 pictures in it. The smaller Phillips show, however, may be a better place to start to get to know Sander. Local collectors Kent and Marcia Minichiello have promised about 40 Sander landscapes to the gallery, and most of those little-known pictures are now on view. They're tucked without fanfare into a pair of rooms between two other shows.

As far as anyone can tell, all these landscapes were shot in the 1930s, but they look almost nothing like other artistic photos of that era. Sander doesn't try to turn them into fancy modern compositions, with the off-kilter points of view, lively thrusts and dynamic balancing of forms of Bauhaus picture-taking. Instead, he sticks to an impressive foursquareness in his views. The subject that matters to him is stuck in the middle of the frame, with incidental detail left to fend for itself across the rest of the picture.

Without further ado, a photograph of a flowering plant from the Brassicaceae family simply offers up its subject for our viewing, caught surrounded by the mess of its native habitat. The image suggests that the lovely blooming plant can speak for itself, without any need for artistic gilding of the lily.

A wonderfully gnarled beech tree similarly takes up the middle of an image, with half its spreading branches out of focus and lopped off by the picture's edge. It's more like a child's honest snapshot of a beloved grandparent than a fancy artist's rendering.

A photo of two marsh plants shows them standing side by side in front of a screen of other plants. They read as entries in a pictorial inventory, rather than as subjects in a fancy botanical portrait session. This kind of picture breaks all the classic rules for elegant composition -- even as recently as 20 years ago, I had photography instructors who taught that this kind of symmetry makes a picture "fall apart" along its central axis. But that fault becomes a virtue in a picture that aims to tell the truth without embellishment.

"The nature of all photography is documentary. . . . In documentary photography, it is less important to observe aesthetic rules in form and composition, but instead to focus on the meaning of the image," said Sander, around the time that he was taking his landscape photographs.

But I think it's a mistake to take him at his word. If giving information about the subject really mattered most, the pseudo-scientific purity of Bauhaus modernism might have done a better job. It's harder to "get" those marsh plants amid the chaos of unvarnished truth than it would have been in a more calculated composition.

I don't think Sander's goal is actually documentary. He is an artist, after all, not a scientist; he thought of himself as one, moved among the self-declared "progressive artists" of Cologne and was touted by museum heads. What he's after in his photographs is an artistic act that captures the look and feel and attitude of accidental, unartistic observation. They're an early archetype of a disingenuous, styleless style that caught on later.

It took until the 1960s, with the work of Lee Friedlander and eventually of photographers like Washington's own John Gossage, for photography to grab onto the feeling of appealingly flat-footed haphazardness that you see already in Sander. Friedlander's messy, straight-ahead pictures of desert cactuses, set in the middle of the frame or caught in a larger tangle of shadows and distracting lines, are close analogues to the plant pictures that Sander had taken decades before.

At his most aggressively anti-aesthetic, Sander created pictures that would not be paralleled until the 1990s, when an ascetic, documentary approach to taking photographs -- think of Nan Goldin -- became the norm on art's cutting edges.

The tension between information and style that the nature photos hint at becomes a full-blown conflict in Sander's famous portrait project. Many Washingtonians may already know some of the most striking of these pictures. Gerd Sander, the artist's grandson, showed them in the photography gallery he opened in Washington in the 1970s. (Local photo dealer Kathleen Ewing still stocks portraits printed by Gerd from Sander's negatives.) The problem is that the sensitive Sander portraits most people know -- the ones sold in galleries and anthologized in photo surveys -- don't really do any kind of justice to how anti-aesthetic the project as a whole can be. The full spread of vintage prints in the Met exhibition should wake viewers up to the real complexities of Sander's artmaking.

There's also a new seven-volume, 619-image book -- $100 through the Met -- that takes a stab at reconstructing what a complete "People of the 20th Century" might have looked like, using new prints for images that survive only as negatives. Those volumes make Sander out to be even more interesting than his biggest fans could have imagined.

The book's dust jacket gives the standard take on Sander: "His intention was for numerous individual portraits, arranged in groups according to occupational, social or family criteria, to reflect the various classes and elements of society, and thus together create a 'picture of the age.' " But if that was truly Sander's stated intention, he joins a long roster of artists who haven't had a clue of what their work is really all about.

The exquisite Sander portraits that get reprinted again and again do point to your standard catalogue of human types. The chubby pastry cook, proudly stirring some batter, demonstrates the kind of aristocratic poise that can come with an honestly practiced craft. The smiling pair of boxers look predictably, happily addled. The upper-class, overdressed frat boy shows off a faceful of dueling scars, but there's doubt in his eyes.

Seeing these images, it's not hard to imagine Sander's work as a kind of heartfelt inventory of humanity, organized along its natural fracture lines: "The Young Farmer," "The Master Craftsman," "The Elegant Woman" are the titles of some of the 50 or so portfolios that Sander arranged his project into. Sander is often billed as doing for the German people what his famous successors Bernd and Hilla Becher did in their photographic catalogues of water towers and steel mills.

But for every eloquent picture that seems to speak of a sitter's self and role in life, there are others in Sander's project that are almost entirely mute, sometimes almost impressively dull. In a picture of two Gypsy women, the faces are so blurred that there's not much chance of reading anything out of them. Many of the men in Sander's "Businessman" portfolio are more or less interchangeable; it's a safe bet that Sander pulled them from the files of his commercial practice, where they would have been commissioned for generic corporate use. (Before the Nazis went after him as a suspiciously liberal-minded character, Sander had run a successful mainstream studio.)

A good few of the pictures of farmers and tradesmen barely give a clue to their sitters' occupations: They show people in their buttoned-up Sunday best. These banal portraits also must have been culled from Sander's commercial work, paid for by sitters keen on concealing roots and occupation, even personality, behind fine cloth.

As for the categories Sander uses to divvy up the world, not all of them group things as crisply as you might imagine. "The Street and Street Life," or portfolios such as "The Radio" and "Traffic" whose original contents have been lost over the years, don't stand out as part of an obvious classifying scheme, the way a grouping like "The Soldier" might. And the category "People Who Came to My Door" sounds like the almost arbitrary sorting tool you get in conceptual art in the 1960s, when artists were looking to cede control of their decision-making. It recalls projects like Ed Ruscha's "Every Building on the Sunset Strip," a hugely influential book of photographs from 1966.

In Europe, there had been a long tradition of images meant to capture the most characteristic face that different kinds of people present to the world -- Diderot's Encyclopedie was full of pictures of the craftsman with his trademark tools. In the 19th century, anthropologists and racists even distilled this into the idea of the "type photograph," a mug shot that would capture crucial, unchanging features of the globe's ethnic and social groups. Sander is often billed as a late, great contributor to this tradition, but with a particularly humane take on it. He's seen as bearing thorough, feeling witness to the full Family of Man. I think that gets "The People of the 20th Century" almost completely wrong.

What's striking about the project isn't how well it sorts the world into compelling categories. It's how splendidly it fails in the attempt. The natural haphazardness captured in each of the Phillips Collection landscapes is the governing principle behind Sander's entire portrait project.

Sander sets up a strange, often incoherent sorting system for the world, and then sets out to fill the niches he's created. He trawls through the vast compendium of images he has at his professional disposal, taken between 1892 and 1954, and pulls out any picture that will fit one of his pigeonholes -- whether it illustrates the subject at hand or not. The pictures range from Sander's first amateurish shots to sensitive examples of the portraitist's art to forgettable hackwork: They are readymades, really, chosen for what they are and what Sander can do with them, rather than for how they look. Only Sander could know that the unremarkable picture of a suited man he titles "Pharmacist" depicts the professional he says it does, rather than the equally nondescript "Dentist" who joins him in Sander's "Doctor" portfolio. We have to take Sander's word for it that his young farmers really work the land; most of his pictures show them dressed in their townwear.

It's as though Sander's project sets out to test the ancient notion that his sitters' looks ought to reflect the people that they are in life. He picks out categories, finds images he knows are supposed to fill them -- and then leaves us to discover that there's hardly a close match between the two. Which is much more important than convincing us that pastry cooks sometimes look as we imagine pastry cooks should look.

Some of Sander's odder categories seem devised to make this point almost explicitly. Germany's Jews aren't given their own ethnic portfolio -- quite. They're included within a larger grouping called "The City," in their own separate portfolio that's titled "The Persecuted." Their essential it-ness as a group doesn't depend on a shared religion, Biblical roots or unalterably hooked noses. They only become a crucial social category because of how they're treated by the people all around them -- change the treatment and the category simply disappears.

The project implies a full repudiation of the kind of social sorting that led to the Nazis. It doesn't merely "humanize" that sorting, as the standard Sander cliche proclaims.

Then there are the people who manage to illustrate the purported "essence" of more than one social category. One bow-tied man is presented as the archetype of "The Arbitrator," in a portfolio labeled "The Judge and the Attorney." But a little digging shows he's already turned up once before, in precisely the same clothes, as the paterfamilias in a group shot titled "Farming Family." If the same image can illustrate two different ideas, how tight a fit can there really be between each pigeon and its unique pigeonhole?

And, on at least one occasion, a sitter turns out to be such a chameleon that he changes his look and the social category he belongs to, at will. Raoul Hausmann, a player on the radical Berlin art scene, doesn't appear in any of the portfolios that Sander groups together as "The Artists." Instead, he first gets dressed up in a natty suit and monocle to play the "Inventor and Dadaist," pretty much indistinguishable from all the tidy technocrats who appear alongside him in one portfolio. And then we see him again in a grab-bag portfolio called "Types and Figures of the City," now shirtless and barefoot in a bohemian's drawstring pants, in an image titled "Raoul Hausmann as Dancer."

It's that word "as" -- the only "as" in the whole project -- that gives the game away. Hausmann's absurdist, Dada principles allow him to present himself to and in the world both "as" a dancer and a Dadaist inventor (whatever that could be). He can bend reality and social categories to suit his whim. Sander's project does the same. It pretends to be a rigorous, technocratic study of the human race. But it really turns out to be a wild dance through the unfiltered mess that is reality.

"People of the 20th Century" revels in the systems and categories we all use to describe the world: Some of its lovely portraits set them up as though there's something there, while its coarser pictures joyfully knock them down.

Aggressively anti-aesthetic: Sander's 1936 "Beech Tree," part of a new show at the Phillips Collection."Young Farmers," part of Sander's "People of the 20th Century" series at the Metropolitan Museum. Early archetypes of a straight-ahead style that caught on later: Dadaist artist Raoul Hausmann, in dancer's garb, in a 1929 photo. The subject of the 1928 "Pastrycook" posed for Sander 14 years earlier for "Widower," far right. A sense of flat-footed haphazardness: Foursquare photographs that suggest the plants can speak for themselves, without any artistic gilding of the lily.Sander shot this profile of painter Otto Dix in 1924.