Question: Who is this Finnish composer and violinist of the late Romantic and early-modern periods that the Scottish music critic and composer Cecil Gray published books on?

Context paragraphs:
David Johnson (Scottish composer): David Charles Johnson (27 October 1942 in Edinburgh – 30 March 2009 in Edinburgh) was a Scottish composer and a scholar of 18th century Scottish music.  Dr David Johnson was ‘an internationally recognised scholar’, whose work did much to rediscover and reinvent 18th century Scottish music, and set it in its historical context.  Johnson’s key legacy is to leave behind a body of writing and editions which throws light on the music and wider social life of 18th century lowland Scotland, its influences and tastes, and the key musical figures within it.

Leevi Madetoja: Leevi Antti Madetoja (] ; 17 February 1887, Oulu – 6 October 1947, Helsinki) was a Finnish composer, music critic, conductor, and teacher of the late-Romantic and early-modern periods; he is generally considered to be among the most significant Finnish composers to emerge after Jean Sibelius, under whom he studied privately from 1908–10.  The core of Madetoja's oeuvre consists of a set of three symphonies (1916, 1918, and 1926), arguably the finest early-twentieth century additions to the Finnish canon of any composer, Sibelius excepted.  As central to Madetoja's legacy is his opera, "The Ostrobothnians" (1924), dubbed Finland's "national opera" following its successful premiere and, even today, a stalwart of its repertoire.  Madetoja's other notable works include an "Elegia" for strings (1909); "The Garden of Death" (1918–21), a three-movement suite for solo piano; the "Japanisme" ballet-pantomime, "Okon Fuoko" (1927); and, a second opera, "Juha" (1935).

March law (Anglo-Scottish border): March law (Anglo-Scottish border) (or Marcher law, or laws and customs of the marches) was a system of customary international law dealing with cross-border dispute settlement, operating during the medieval and early-modern periods in the area of the Anglo-Scottish border or Anglo-Scottish marches - the word "march" being the Old English form of the Old French word "marche" meaning "boundary" (the Anglo-Welsh border and the Anglo-Irish marches had their own versions of "the Law of the Marches").  They were " essentially a set of regulations for the prosecution of offences committed by the inhabitants of one country inside the territory of the other, and for the recovery of property stolen or lent across their common border."

Jean Sibelius: Jean Sibelius ( ;    ), born Johan Julius Christian Sibelius (8 December 186520 September 1957), was a Finnish composer and violinist of the late Romantic and early-modern periods.  He is widely recognized as his country's greatest composer and, through his music, is often credited with having helped Finland to develop a national identity during its struggle for independence from Russia.

Esquire of the Body: An Esquire of the Body was a personal attendant and courtier to the Kings of England in the late-medieval and early-modern periods.  The position also existed in some lesser courts, such as that of the Prince of Wales.

Jesse Glenn Gray: Jesse Glenn Gray (known as "J. Glenn Gray"; 1913–1977) was an American philosopher, writer, and professor of philosophy at Colorado College.  Gray published numerous books and essays.  His first major publication, "", is a philosophical memoir of his years as an counter-intelligence officer near the battle lines in Italy during World War II inspired by Gray’s opposition to war.  Its reprint in 1967 and subsequent editions included an introduction by Hannah Arendt.

Cecil Gray (composer): Cecil Gray (1895–1951) was a Scottish music critic and composer.  He published books on the composers Jean Sibelius, Peter Warlock and Carlo Gesualdo, the last of these co-authored by the same Warlock; also a history of music, collections of essays on music, a play about Gilles de Rais and an autobiography.

Villa Solitaria: Villa Solitaria was the home of the Scottish writer Compton Mackenzie when he lived on Capri, Italy.  It was also used by the Scottish music critic and composer, Cecil Gray.  Set on a bluff, it was built by architect Edwin Cerio in the early 20th century.

Toivo Kuula: Toivo Timoteus Kuula (7 July 1883, Vaasa – 18 May 1918, Viipuri) was a Finnish composer and conductor of the late-Romantic and early-modern periods, who emerged in the wake of Jean Sibelius, under whom he studied privately from 1906 to 1908.  The core of Kuula's oeuvre are his many works for voice and orchestra, in particular the "Stabat mater" (1914–18; completed by Madetoja), "The Sea-Bathing Maidens" (1910), "Son of a Slave" (1910), and "The Maiden and the Boyar's Son" (1912).  In addition he also composed to "Ostrobothnian Suites" for orchestra and left an unfinished symphony at the time of his death in 1918.

Taneli Kuusisto: Taneli Kuusisto (19 June 1905 – 30 March 1988) was a Finnish composer, music critic, teacher and choir leader.

Supporting paragraphs: Cecil Gray (composer) Jean Sibelius
Answer: Jean Sibelius