Edgard Varèse completed Intégrales in 1925. It is scored for woodwinds, brass, and 17 different percussion instruments played by four percussionists. Varèse's term "spatial music" was first applied to this work, which broadly denotes a concept that pertains to all of his surviving output. It was his way of depicting music as a collection of coexisting sound properties (melody, harmony, rhythm, etc.). Instruments are chosen for the specific aspect of music they do best (the composer preferred winds and percussion) and they appear in sonic groupings that occur in different temporal durations from one another. This was dubbed "spatial" music because it is easier to describe it in terms of physical and temporal space; the durations among the different blocks of sound drift closer and further apart while appearing and reappearing in variations of themselves. Tensions vary in accordance the proximity of the sound blocks.
Intégrales is dedicated to Juliana Force, and its title is not meant to denote an association with anything extra-musical. One of Varèse's former students pointed out that this work was written in spite of the limitations of conventional instruments and notation, that the world of sound contained in this piece is not about the instruments, but the distinction of the timbres between them. Instruments are intended to either blend or contrast with other instruments depending on whether or not they are in the same sound "block." Many listeners feel that this ambivalence to instruments made Varèse better suited to music that excludes them, such as tape music, which he eventually turned to. He said that the future of sounds required composers and electrical engineers to find the solution to the outdated means of generating notes. This geometric and abstract approach to music came to him while listening to the scherzo of Beethoven's Seventh Symphony, which inspired in him a sense of, in his own works, "projection in space." Intégrales lends itself to visual impressions of celestial bodies in motion. The composer said that mathematics and astronomy inspired him; the motion of planets revolving around a star is comparable to the blocks of sound heard in this piece.
The premiere of Intégrales was peculiar because it was so well received by the general public. At the Aeolian Hall in New York, Leopold Stokowski conducted it on March 1, 1925 to an enthusiastic crowd. This was not a group of avant-garde enthusiasts, but a more or less traditional audience who enjoyed the work so much that Stokowski was obliged to perform it again that evening. However, other than a few admiring writers, the critics hated Intégrales and mocked the piece at length. It is possible that this work offended the sensibilities of a writing community that had spent years building a meaningful way of talking about new music. Varèse's output still eludes easy description and the vast majority of musical terms and ideas available to listeners and writers do not pertain to his style. His own descriptions of his works are often opaque. Listeners without an extended musical vocabulary have the advantage of not instinctually attempting to turn the experience of Intégrales into words.