The 'Large Glass' is one of the most celebrated avant-garde works in the history of modern art. To make it Duchamp used dramatically unconventional materials and techniques including chance procedures. Duchamp sought to establish that a work of art can take any form that the artist considers appropriate to his ideas and can be made of any materials the artist thinks fit. This was an important freedom for modern artists and led to some extremely interesting later developments.
The 'Large Glass' has always resisted interpretation; Duchamp himself, in 1934, published 'The Green Box', a flat case containing replicas of 94 items of notes, drawings, and photographs relating to the creation of the 'Large Glass'. From this it is fairly clear that part of his intention was to create an ironic image of human love-making as a mechanistic and endlessly frustrating process. The top half of the work represents the Bride, the lower half the Bachelors, and the whole seems to represent the ritual climax of the kind of traditional wedding ceremony at which the bride was formally disrobed and put to bed with her new husband in the presence of witnesses.
The Bride is provided with no less than nine Bachelors, the upright forms in the lower glass, which Duchamp also named the Malic Moulds, a pun on both the word male and phallic. The Bride is represented by the mechanical elements on the left of the upper glass. The pink cloud, called the Blossoming, represents her rising desire for the Bachelors and from within it she signals to the Bachelors with the three elements which suggest flag-like waving rectangles of cloth. The Bachelors respond by producing Illuminating Gas which they pump along Capillary Tubes to the cone-shaped Sieves. Duchamp stopped work at this point and pronounced the Glass 'definitively unfinished' but we know that the Illuminating Gas would have emerged from the end of the chain of sieves, splashed down in the empty lower right part of the Glass and was then directed upwards through the centres of the four circular elements, the Oculist Witnesses, to land finally near the tip of the Blossoming. Duchamp did represent its landing, by the scatter of holes in the Glass known as the Shots. The whole sequence forms a disguised account of an incomplete sexual act.
Most of the work was done with oil paint backed by lead foil. But the contents of the Sieves were originally created by allowing dust to settle on the Glass, which Duchamp placed flat on trestles by the open window of his New York apartment and left for more than a year. The position of the Shots' was determined by firing paint-tipped matches at the Glass from a toy cannon, and the Oculist Witnesses were created by having the Glass mirror silvered and then scraping away to form the patterns, which are based on a type of optician's eye testing chart.
Simon Wilson, Tate Gallery: An Illustrated Companion, Tate Gallery, London, revised edition 1991, p.159