Task: Question Answering
Input (English): Passage: A few composers have written symphonies for unaccompanied chorus, in which the choir performs both vocal and instrumental functions. Granville Bantock composed three such works—Atalanta in Calydon (1911), Vanity of Vanities (1913) and A Pageant of Human Life (1913). His Atalanta, called by musicologist Herbert Antcliffe "the most important [work of the three] alike in technical experiment and in inspiration", was written for a choir of at least 200, the composer specifying "'not less than 10 voices for each part,'" a work with 20 separate vocal parts. Using these forces, Bantock formed groups "of different weights and colors to get something of the varied play of tints and perspective [of an orchestra]". In addition, the choir is generally divided into three sections, approximating the timbres of woodwinds, brass and strings. Within these divisions, Antcliffe writes,
Almost every possible means of vocal expression is employed separately or in combination with others. To hear the different parts of the choir describing in word and tone "laughter" and "tears" respectively at the same time is to realize how little the possibilities of choral singing have as yet been grasped by the ordinary conductor and composer. Such combinations are extremely effective when properly achieved, but they are very difficult to achieve.
Roy Harris wrote his Symphony for Voices in 1935 for a cappella choir split into eight parts. Harris focused on harmony, rhythm and dynamics, allowing the text by Walt Whitman to dictate the choral writing. "In a real sense, the human strivings so vividly portrayed in Whitman's poetry find a musical analog to the trials to which the singers are subjected", John Profitt writes both of the music's difficulty for performers and of its highly evocative quality. Malcolm Williamson wrote his Symphony for Voices between 1960 and 1962, setting texts by Australian poet James McAuley. Lewis Mitchell writes that the work is not a symphony in any true sense, but rather a four-movement work preceded by an invocation for solo contralto. The text is a combination of poems celebrating the Australian wilderness and visionary Christianity, its jagged lines and rhythms matched by the music. Mitchell writes, "Of all his choral works, with the possible exception of the Requiem for a Tribe Brother, the Symphony is the most Australian in feeling". 
Question: What work did Lewis Mitchell claim was not a symphony, but rather a four-movement work?
Output (English): Symphony for Voices.