Jean-Jacques Rousseau (28 June 1712 – 2 July 1778) was a Genevan philosopher, writer, and composer of 18th-century Romanticism. His political philosophy influenced the French Revolution as well as the overall development of modern political, sociological and educational thought.
His novel Émile: or, On Education is a treatise on the education of the whole person for citizenship. His sentimental novel Julie, ou la nouvelle Héloïse was of importance to the development of pre-romanticism and romanticism in fiction. Rousseau's autobiographical writings — his Confessions, which initiated the modern autobiography, and his Reveries of a Solitary Walker — exemplified the late 18th-century movement known as the Age of Sensibility, featuring an increasing focus on subjectivity and introspection that has characterized the modern age. His Discourse on the Origin of Inequality and his On the Social Contract are cornerstones in modern political and social thought and make a strong case for democratic government and social empowerment.
Rousseau was a successful composer of music, besides. He wrote seven operas as well as music in other forms, and he made contributions to music as a theorist.
During the period of the French Revolution, Rousseau was the most popular of the philosophes among members of the Jacobin Club. He was interred as a national hero in the Panthéon in Paris, in 1794, 16 years after his death.
Source: Wikipedia, "Jean-Jacques Rousseau", available under the CC-BY-SA License.