Alexis de Tocqueville (1805-1859) was a French thinker, jurist, politician and historian precursor of classical sociology and one of the most important ideologist of liberalism.
His intellectual restlessness led him to accept a government mission to travel to the US to study its penitentiary system (1831) and his stay there lasted nine months. The result of this trip was his first book: Of the penitentiary system in the United States and its application in France (1833). However, his stay in the United States served to deepen the analysis of American political and social systems, which he described in his book Democracy in America (1835-1840).
