Happy Birthday: Jean-Jacques Rousseau (28 June 1712 – 2 July 1778) was a Genevan philosopher (philosophe), writer, and composer. His political philosophy influenced the progress of the Age of Enlightenment throughout Europe, as well as aspects of the French Revolution and the development of modern political, economic, and educational thought.

His Discourse on Inequality, which argues that private property is the source of inequality, and The Social Contract, which outlines the basis for a legitimate political order, are cornerstones in modern political and social thought. Rousseau's sentimental novel Julie, or the New Heloise (1761) was important to the development of pre-romanticism and romanticism in fiction. His Emile, or On Education (1762) is an educational treatise on the place of the individual in society. Rousseau's autobiographical writings—the posthumously published Confessions (completed in 1770), which initiated the modern autobiography, and the unfinished Reveries of the Solitary Walker (composed 1776–1778)—exemplified the late 18th-century "Age of Sensibility", and featured an increased focus on subjectivity and introspection that later characterized modern writing.

Rousseau based his political philosophy on contract theory and his reading of Thomas Hobbes. Reacting to the ideas of Samuel von Pufendorf and John Locke was also driving his thought. All three thinkers had believed that humans living without central authority were facing uncertain conditions in a state of mutual competition. In contrast, Rousseau believed that there was no explanation for why this would be the case, as there would have been no conflict or property. Rousseau especially criticized Hobbes for asserting that since man in the "state of nature... has no idea of goodness he must be naturally wicked; that he is vicious because he does not know virtue". On the contrary, Rousseau holds that "uncorrupted morals" prevail in the "state of nature".