Conceived in 1948, while Cage was working on Sonatas and Interludes, 4′33″ was for Cage the epitome of aleatoric music and of his idea that any sounds constitute, or may constitute, music. It was also a reflection of the influence of Zen Buddhism, which Cage studied since the late 1940s. In a 1982 interview, and on numerous other occasions, Cage stated that 4′33″ was, in his opinion, his most important work.
There has been some skepticism about the accuracy of the engineer's explanation, especially as to being able to hear one's own nervous system. A mild case of tinnitus might cause one to hear a small, high-pitched sound. It has been asserted by acoustic scientists that, after a long time in such a quiet environment, air molecules can be heard bumping into one's eardrums in an elusive hiss (0 dB, or 20 micropascals). Whatever the truth of these explanations, Cage had gone to a place where he expected total silence, and yet heard sound. "Until I die there will be sounds. And they will continue following my death. One need not fear about the future of music." The realisation as he saw it of the impossibility of silence led to the composition of 4'33″.
Cage wrote in "A Composer's Confessions" (1948) that he had the desire to "compose a piece of uninterrupted silence and sell it to the Muzak Co. It will be 4 [and a half] minutes long — these being the standard lengths of 'canned' music, and its title will be 'Silent Prayer'. It will open with a single idea which I will attempt to make as seductive as the color and shape or fragrance of a flower. The ending will approach imperceptibly."
Another cited influence for this piece came from the field of the visual arts. Cage's friend and sometimes colleague Robert Rauschenberg had produced, in 1951, a series of white paintings, seemingly "blank" canvases (though painted with white house paint) that in fact change according to varying light conditions in the rooms in which they were hung, the shadows of people in the room and so on. This inspired Cage to use a similar idea, as he later stated, "Actually what pushed me into it was not guts but the example of Robert Rauschenberg. His white paintings… when I saw those, I said, 'Oh yes, I must. Otherwise I'm lagging, otherwise music is lagging'." Cage's musical equivalent to the Rauschenberg paintings uses the "silence" of the piece as an aural "blank canvas" to reflect the dynamic flux of ambient sounds surrounding each performance; the music of the piece is natural sounds of the players, the audience, the building, and the outside environment.
Cage was not the first composer to conceive of a piece consisting solely of silence. One precedent is "In futurum", a movement from the Fünf Pittoresken for piano by Czech composer Erwin Schulhoff. Written in 1919, Schulhoff's meticulously notated composition is made up entirely of rests. Cage was, however, almost certainly unaware of Schulhoff's work. Another prior example is Alphonse Allais's Funeral March for the Obsequies of a Deaf Man, written in 1897, and consisting of nine blank measures. Allais's composition is arguably closer in spirit to Cage's work; Allais was an associate of Erik Satie, and given Cage's profound admiration for Satie, the possibility that Cage was inspired by the Funeral March is tempting. However, according to Cage himself, he was unaware of Allais's composition at the time (though he had heard of a 19th-century book that was completely blank).
Richard Kostelanetz suggests that the very fact that Tudor, a man known for championing experimental music, was the performer, and that Cage, a man known for introducing unexpected non-musical noise into his work, was the composer, would have led the audience to expect unexpected sounds. Anybody listening intently would have heard them: while the performer produces no deliberately musical sound, there will nonetheless be sounds in the concert hall (just as there were sounds in the anechoic chamber at Harvard). It is these sounds, unpredictable and unintentional, that are to be regarded as constituting the music in this piece. The piece remains controversial to this day, and is seen as challenging the very definition of music.
The title and therefore the length of 4'33″ is in fact not designated by its score. The instructions for the work indicate that it consists of three movements, for each of which the only instruction is "tacet," indicating silence on the part of the performer or performers. The title of the piece in each performance is determined by the length of silence chosen. Cage chose the length of the famous premiere performance by chance methods using I Ching models, the results of which happen to coincide with average lengths of pieces of so-called 'canned' music, where the applicability of those models is valid too, because both fields are dealing in some or the other way with the attentiveness and concentration abilities of humans. There is no evidence supporting the claim that Cage chose the length deliberately.
On January 16, 2004, at the Barbican in London, the BBC Symphony Orchestra gave the UK's first orchestral performance of this work. The performance was broadcast live on BBC Radio 3, and one of the main challenges was that the station's emergency backup systems are designed to switch on whenever apparent silence (dead air) is detected. They had to be switched off for the sole purpose of this performance.
A tongue-in-cheek version was recorded by the staff of the UK Guardian newspaper on 2004-01-16. A (probably fictitious) story tells that a 7" vinyl version of 4'33″ was at one time popular on the juke boxes of a number of bars, as it gave customers a relief from an otherwise relentless soundtrack of rock and roll.
A performance of 4'33″ was broadcast on Australian radio station ABC Classic FM, as part of a program exploring "sonic responses" to Cage's work. A mocking, jazz version (not following the score) was performed as part of The Fast Show on BBC.
The BBC series The Fast Show recorded a jazz version of 4'33″ as part of their Jazz Club segment. The fact that their version only lasted roughly 90 seconds was put down to the need for artistic expression and thrusting as part of jazz, and that any piece of music was open to an artist's interpretation.
Italian electronic/experimental producer Dj Batman released a cover of 4'33″ via BeatsDigital.com on March 4th, 2008. In this case, silence was entirely computer-generated.
The second performance added four new qualifications to the directions: "the performer should allow any interruptions of the action, the action should fulfill an obligation to others, the same action should not be used in more than one performance, and should not be the performance of a musical composition."