Yves Klein's celebrated, although cumbrously titled 1958 exhibition La spécialisation de la sensibilité ŕ l'état matičre premičre en sensibilité picturale stabilisée: Le Vide (The Specialization of Sensibility in the Raw Material State into Stabilized Pictorial Sensibility: The Void) provides art history with its first truly notable engagement with the immaterial artwork.
By removing everything except a large cabinet from the gallery space and painting every surface white (left), Klein's proposition was that the aura of his presence was artwork enough. ("I will concentrate alone in the room, and then present a sensitive pictorial space to the public", he said at the time).
Archive film footage (below) depicts the artist striding about the empty space, contemplating its bare walls while appearing to take the measure of impalpable artworks.
Klein's invisible spectacle was a triumph. Three thousand visitors arrived for the opening night alone, and several hundred a day subsequently poured into the tiny gallery, which extended the exhibition for a week to accommodate the numbers.
Yet its success was far from entirely due to what was (not) on show.
Klein, for all his reductionist tendencies, was also a master of self-publicity, organising various stunts and advertising strategies amounting - somewhat perversely - to an art of excess.
Such manoeuvres included mail-outs featuring International Kleinian Blue postage stamps, while the gallery window for 'Void' was painted ultramarine and a sumptuous blue curtain hung in the lobby. At the vernissage, Republican guards stood sentry at the doorway and blue cocktails were served to guests.
The prevailing mythology surrounding Klein's 1958 show remains, however, one of absence rather than abundance: a radical embrace of nominally empty space that was quickly adopted by other artists and is still being echoed in the exhibition strategies of numerous contemporary figures.
US artist Robert Barry's Closed Gallery Piece, (above) extends the legacy of Klein's empty gallery into a space that is not just void of physical content, but physically inaccessible besides.
Exhibited from 1969 to 1970 at galleries in Los Angeles, Amsterdam and Turin, Barry's work consists solely of a notice informing would-be viewers that the space is closed for the duration of the exhibition.
A similar piece, Some places to which we can come, and for a while be free to think about what we are going to do was debuted in 1970.
With this work, Barry invites the visitor to consider the exhibition space not just in terms of what it has to show, but as a place to meet and reflect.
Barry's important engagement with minimalism and, from the late 1960s onwards, conceptual art, would also lead to the development of many other immaterial artworks, several of which are described in other sections of this article.
Argentinean artist Carnevale's infamous 1968 work converted an empty gallery into a site of political action and commentary (left).
Guests invited to an opening found themselves in an empty store whose windows had been partially covered with posters.
Once all were gathered inside, the artist locked the door, leaving attendees trapped for an hour until a passerby smashed a window and allowed them to escape.
As they exited, each 'participant' was handed a statement drawing parallels between their own experience and the abusive acts perpetrated daily by the Argentine military government.
While partially reprising Klein's show of absence, Robert Irwin's Experimental Situation, (Ace Gallery, Los Angeles, 1970) is a far more tentative engagement with empty space notionally filled with the presence of the artist.
As the invitation to the exhibition explained, "The gallery (...) will be empty for a period of 1 month (October), for Robert Irwin to visit the space daily to conceive the different possibilities of artworks for the space."
Taking place at a point in Irwin's career when he was questioning the validity of his earlier work as a painter, Experimental Situation was predicated, exactly as its name implies, as a period of contemplation and experiment.
Far from the triumphant affirmation of self that energises Klein's piece, Irwin's approach suggests a void that requires filling. This meditative strategy in fact functioned beautifully, resulting in Scrim Piece (1971), the first of the artist's acclaimed works using polyester fabric.
In a gallery empty of everything but the artist himself, Chris Burden's 1975 performance White Light/White Heat (above) was also essentially unviewable.
Lying for twenty-two days on a triangular platform high above visitors' heads, Burden neither ate, nor spoke during his self-imposed confinement.
Elliptically testing Klein's proposition that the aura of an artist can be intensely felt, Burden's action augments this notion through an emphasis on his own privation.
By negating, as much as possible, the physical circumstances of his presence, Burden circuitously succeeded in affirming it all the more.
Dutch artist Stanley Brouwn, an almost legendary figure whose practice is marked by insistence on various absences - he does not, for example, allow his work to be officially documented, and is famously reclusive - first created 'how empty is this space?' for an eponymous exhibition held at the Städtisches Museum Mönchengladbach, Germany in 1970.
The text, which is intended to be mounted in an otherwise vacant gallery space, reads:
'how empty is this
all the planets, thus including planet earth, constantly find themselves in a "shower" of cosmic rays
in this space, as in every building on earth, it is also "raining cosmic rays"
walking consciously through the invisible cosmic rays
in this space confirms, intensifies
the presence of this space'
Transforming the gallery through an emphasis on invisible presence, the artist advocates a very different experience of focus and reflection in which no tangible, or indeed, man-made, artwork is involved.
In addition, his almost casual insistence that the wondrous "cosmic rays" to which he refers exist "in every building on earth", subtly undermines the art institution as a principal locus of meditative engagement, suggesting that its only real purpose, as here, is to direct attention to an ultimate 'artwork' that can be freely experienced anywhere.
Asher's complex and largely under-appreciated practice involves a questioning of institutional space characterised by often almost imperceptible interventions.
One such piece created for the Claire Copley Gallery, Los Angeles, in 1974, (below) involved the removal of a partition wall shielding office from exhibition area, redefining the gallery as a site of administrative, economic and bureaucratic procedure rather than as a rarefied location for the contemplation of art.
For a work created the same year at the Novia Scotia College of Art and Design's Anna Leonowens Gallery (below), Asher requested that the lights remain off in order to allow the space to "... be perceived solely as an architectural volume uninflected by details or fixtures".
Tinted sunscreens were removed from the plate-glass window wall as "...they were not a part of the original design windows and would have modified the normal quality of interior light" and, finally, the secretary who usually presided over the space was made temporarily absent.
Asher described his reasoning behind the work in detail, stating that it
"... was concerned with the minimal amount of modification to the gallery space itself.
In part, it showed that any space defined as a gallery would be perceived as such by the viewer, whether or not objects were being exhibited there.
The absence of objects, in this case, first objectified the architectural space and design details and then shifted the viewers' attention to their own preconceptions of what an exhibition should look like.
Ultimately, the viewers were left to decide to what degree they might have been the subject of this exhibition or whether they were supposed to project some imaginary exhibition into the space."
See also: architectures of air
The empty galleries characterising Maria Eichhorn's 2001 show Money at the Kunsthalle Bern, Switzerland, were, as its title indicated, all about finance - or in this case, an alarming lack of it.
With the artist choosing to allocate her show's budget to long-overdue repairs on the museum building itself, the renovations were listed, along with their cost, on the exhibition poster and accompanying catalogue cover.
Visitors to the show experienced the results of Eichhorn's gesture first-hand as plumbers, electricians and builders set about their work.
The catalogue text itself - the most tangible aspect of the show, apart from the works undertaken - consisted of a detailed history of the Kunsthalle with an emphasis on its financing systems.
Although intended as an alternative portrait, Eichhorn's research in fact revealed a a long history of mismanagement, including the fact that money granted for repairs had repeatedly been used for other purposes.
Her philanthropic gesture was therefore transformed into a very different critique, placing the Kunsthalle, rather than funding bodies, firmly at the centre of its history of neglect.
David Hammons' 2002-3 exhibition Concerto in Black and Blue took place in a cavernous, unlit New York gallery space which visitors were able to explore using tiny blue LED torches.
Reminiscent of the 1938 International Surrealist Exhibition, which was also lit only by visitors' flashlights, Hammons' show, by contrast, provided no artworks to observe.
Instead, the entire piece consisted of the interplay between moving light and an otherwise enveloping darkness - and of the rich layers of meaning suggested by the two colours involved.
'Black' and 'blue' conjure particularly powerful associations with regard to Hammon's own identity as an African American; most obviously through an evocation of the Blues as both musical genre and key 'document' of black American history.
Originating among the slave plantations of the South, the development of the Blues is marked by privation and cruelty, its very name foregrounding intense melancholy.
The traumatic nature of such a history is further underscored by the phrase 'black and blue' and its associations with violent bruising.
Yet Concerto in Black and Blue also seems to seek reconciliation of a sort. Through a title that conflates the mournfulness of the Blues with the classical form of the concerto (the three movements of which can feature almost any emotional register, but are, perhaps, most often associated with vivacious, uplifting rhythm), we are also reminded that the concerto is an ensemble piece with a gifted soloist at its core.
Hammons' show, of course, is dependent on such participation.
It also exists as a deft repudiation of art as commodity, a theme which consistently preoccupies the artist. By initiating acts of contemplation, communion and, particularly, discovery, Hammon's objectless exhibition calls into question the art world's overwhelming emphasis on saleable artefacts.
The Empty Museum (2004, above) by Russian-born American artists Ilya and Emilia Kabakov, turns exhibition space, rather than its conventional contents, into an object of contemplation.
Ostensibly replicating a 'classical' painting gallery, any real similarities are undermined by a complete lack of paintings and the loud strains of Bach in what would usually be a silent room.
The tableau resembles a show in some kind of transitional state: paintings not yet hung, or recently removed; a representation of the emptied space artists themselves contemplate before filling it with work.
Yet there's clearly also a finality to the piece, which seems to have been presented as a fait accompli. How, then, to interpret the function of the Kabakovs' museum?
Straightforward answers are enigmatically withheld, but our usual, optical experience of art is conspicuously replaced by something far more impressionistic and immersive.
The empty or apparently vacant gallery is a central figure in the work of Slovakian artist Roman Ondák, continually recurring in subtle pieces that instigate new perceptions of exhibition space and confound expectation regarding the kind of works with which they might be filled.
In 2000, for example, the artist asked friends and family to draw an empty gallery according to his description (Untitled (Empty Gallery), above), the subtle but substantial differences in the results existing as testament to the variation somehow inherent in the idea of the void.
In 2002, Ondák organised tours of an empty Zagreb gallery, and in 2003 submitted plans to the Slovak government for an entirely virtual museum of contemporary art.
More Silent Than Ever (2006, left) consists of an empty room supposedly equipped with hidden listening devices, the presence of which fundamentally alters our perception of emptiness, filling it instead with a mild sense of menace and our own, heightened self-consciousness.
And in one of his more recent works (Loop, for the 2009 Venice Biennale) Ondák played with the notion of invisibility by converting exhibition space into an almost seamless extension of the park grounds in which it was located (below).