Question: Jean-Pierre Leguay studied with which French composer who was one of the major names in his field in the 20th century?
Context: Les nuits d'été ("Summer Nights"), Op. 7, is a song cycle by the French composer Hector Berlioz.  It is a setting of six poems by Théophile Gautier.  The cycle, completed in 1841, was originally for soloist and piano accompaniment.  Berlioz orchestrated one of the songs in 1843, and did the same for the other five in 1856.  The cycle was neglected for many years, but during the 20th century it became, and has remained, one of the composer's most popular works.  The full orchestral version is more frequently performed in concert and on record than the piano original.  The theme of the work is the progress of love, from youthful innocence to loss and finally renewal. Joaquim Soeiro Pereira Gomes (14 April 1909 – 5 December 1949) was a Portuguese writer of realist influence and became one of the major names of Portuguese literature of the 20th century.  Pereira Gomes is, along with Alves Redol, the biggest name of the Portuguese neo-realist movement.  He was also a communist militant and that was always present in its work, the Portuguese Communist Party headquarters (Soeiro Pereira Gomes Building), in Lisbon, are named after him. Darius Milhaud (] ; 4 September 1892 – 22 June 1974) was a French composer, conductor, and teacher.  He was a member of "Les Six"—also known as "The Group of Six"—and one of the most prolific composers of the 20th century.  His compositions are influenced by jazz and Brazilian music and make extensive use of polytonality.  Milhaud is considered one of the key modernist composers. Les nuits d'été ("Summer Nights"), Op. 7, is a song cycle by the French composer Hector Berlioz, setting six poems by Théophile Gautier.  The cycle, completed in 1841, was originally for soloist and piano accompaniment.  Berlioz orchestrated one of the songs in 1843, and did the same for the other five in 1856.  The cycle was neglected for many years, but during the 20th century it became, and has remained, one of the composer's most popular works.  Of the many recordings made in the 20th and 21st centuries, most are of the orchestrated version and are sung by a soprano or mezzo-soprano. Olivier Eugène Charles Prosper Messiaen (] ; December 10, 1908 – April 27, 1992) was a French composer, organist, and ornithologist, one of the major composers of the 20th century.  His music is rhythmically complex; harmonically and melodically he employs a system he called "modes of limited transposition", which he abstracted from the systems of material generated by his early compositions and improvisations.  He wrote music for chamber ensembles and orchestra, as well as for solo organ and piano, and also experimented with the use of novel electronic instruments developed in Europe during his lifetime. Orpheus (full title: Die wunderbare Beständigkeit der Liebe oder Orpheus, "The Wonderful Constancy of Love, or Orpheus") is an opera in three acts by the German composer Georg Philipp Telemann.  It was first performed in a concert version at the Oper am Gänsemarkt in Hamburg on 9 March 1726.  The anonymous libretto is based on "Orphée" by Michel du Boulay, originally set by the French composer Louis Lully.  Most of the work is in German but it also contains passages in French and Italian drawn from famous operas by Handel and Jean-Baptiste Lully.  The music to these words is Telemann's own, however.  The manuscript score of "Orpheus" was not rediscovered until the late 20th century. William Henry Squire, ARCM (8 August 1871 – 17 March 1963) was a British cellist, composer and music professor of the late 19th and early 20th centuries.  He studied cello at the Royal College of Music, and become professor of cello at the Royal College and Guildhall schools of music.  He was principal cello in several major London orchestras and helped to popularize the cello as a solo instrument in the early years of the 20th century by giving public concerts throughout the British Isles and making recordings; he became well known for his performances of the Elgar and Saint-Saëns cello concertos.  In 1893 the French composer Gabriel Fauré dedicated his cello piece "Sicilienne" to Squire.  Squire's own compositions were written mainly for the cello; these included several solo pieces of light character and a cello concerto; he also wrote the music for a number of songs. Ecology is a new science and considered as an important branch of biological science, having only become prominent during the second half of the 20th century.  Ecological thought is derivative of established currents in philosophy, particularly from ethics and politics.  Its history stems all the way back to the 4th century.  One of the first ecologists whose writings survive may have been Aristotle or perhaps his student, Theophrastus, both of whom had interest in many species of animals and plants.  Theophrastus described interrelationships between animals and their environment as early as the 4th century BC.  Ecology developed substantially in the 18th and 19th century.  It began with Carl Linnaeus and his work with the economy of nature.  Soon after came Alexander von Humboldt and his work with botanical geography.  Alfred Russel Wallace and Karl Möbius then contributed with the notion of biocoenosis.  Eugenius Warming’s work with ecological plant geography led to the founding of ecology as a discipline.  Charles Darwin’s work also contributed to the science of ecology, and Darwin is often attributed with progressing the discipline more than anyone else in its young history.  Ecological thought expanded even more in the early 20th century.  Major contributions included: Eduard Suess’ and Vladimir Vernadsky’s work with the biosphere, Arthur Tansley’s ecosystem, Charles Elton's "Animal Ecology", and Henry Cowles ecological succession.  Ecology influenced the social sciences and humanities.  Human ecology began in the early 20th century and it recognized humans as an ecological factor.  Later James Lovelock advanced views on earth as a macro-organism with the Gaia hypothesis.  Conservation stemmed from the science of ecology.  Important figures and movements include Shelford and the ESA, National Environmental Policy act, George Perkins Marsh, Theodore Roosevelt, Stephen A. Forbes, and post-Dust Bowl conservation.  Later in the 20th century world governments collaborated on man’s effects on the biosphere and Earth’s environment. Jean-Pierre Leguay (born 4 July 1939 in Dijon) is a French organist, composer and improviser.  He studied with André Marchal, Gaston Litaize, Rolande Falcinelli (organ), Simone Plé-Caussade (counterpoint), and Olivier Messiaen (composition), before serving as titular organist at in Paris from 1961 to 1984.  In 1985 he was named a titular organist at the Cathedral of Notre-Dame de Paris, alongside Olivier Latry, Yves Devernay and Philippe Lefebvre. The French composer Hector Berlioz made four attempts at winning the Prix de Rome music prize, finally succeeding in 1830.  As part of the competition, he had to write a cantata to a text set by the examiners.  Berlioz's efforts to win the prize are described at length in his "Memoirs".  He regarded it as the first stage in his struggle against the musical conservatism represented by the judges, who included established composers such as Luigi Cherubini, François-Adrien Boieldieu and Henri Montan Berton.  Berlioz's stay in Italy as a result of winning the prize also had a great influence on later works such as "Benvenuto Cellini" and "Harold en Italie".  The composer subsequently destroyed the scores of two cantatas ("Orphée" and "Sardanapale") almost completely and reused music from all four of them in later works.  There was a revival of interest in the cantatas in the late 20th century, particularly "La mort de Cléopâtre", which has become a favourite showcase for the soprano and mezzo-soprano voice.
Answer: Olivier Eugène Charles Prosper Messiaen