Without a doubt, Robert Burns is Scotland's best-known poet and was a prolific composer, writing about 400 songs during his short life, though the extent of his authorship is still unknown. Contemporary records are unreliable, as even he rarely noted which of his songs were set to existing folk melodies and which were his own compositions, making it almost impossible to tell whether he transcribed and added a text or actually wrote the music for such classics as "Coming Through the Rye." While his works are generally sentimental, some of them include mocking social commentary, such as the then shockingly egalitarian "For a' That and a' That." Despite the mythology that has depicted him as an unlettered "ploughman poet," he was given an extensive though informal education despite his family's relative poverty. He avidly read contemporary poetry, as well as classics of English literature. He produced his first poem at 15, writing a text in Scottish dialect, O once I lov'd a soncie lass, to the tune of his sweetheart's favorite reel. He continued to write, while unsuccessfully taking on various agricultural positions, but did not publish until 1786, when he produced Poems, Chiefly in the Scottish Dialect, to finance marriage and migration to Jamaica. The work was a best seller and at the death of his fiancée, he changed his plans and traveled throughout Scotland, settling in Edinburgh. There he found work with a publisher, James Johnson, who gave him the task of editing a multi-volume compendium of folk songs, The Scots Musical Museum. Burns included more than 150 of his own works in this collection, as well as over 100 to another collection, George Thomson's A Select Collection of Scottish Airs, begun in 1793. Burns participated in these projects solely for money; he was an early proponent of the idea that folk songs are art forms of their own right and that polite, semi-classical arrangements dilute their spirit. However, many of his own settings were grudgingly written to appeal to middle- and upper-class audiences, like Haydn's and Beethoven's arrangements of several of his songs. Upon his marriage to Jean Armour, already mother of four of his children, he left Edinburgh to attempt farming again and met with no more success than before. In 1789, he abandoned agriculture altogether and began work as an excise officer. He contracted rheumatic fever and died five years later.