On freedom is a vibrant defense of freedom of thought and expression, a passionate advocacy of tolerance and respect due to dissident beliefs or minorities, a bold claim of spontaneity and human uniqueness in the face of the oppression exercised by the authorities, the custom or the opinion. The present essay by John Stuart Mill (1806-1873) belongs to the brief gallery of political combat works that, even decades or centuries after being written, continue to determine the behavior of men. John Stuart Mill decisively marked liberal democratic thought. On freedom was basically conceived as a protest against the coercive moralism that prevailed in Victorian England. Mill tried to defend a conception of political life characterized by individual freedom, a more responsible government and an efficient administration, free of corrupt practices. Mill saw numerous dangers in the new democratic tendencies of nineteenth-century society. He feared, like Tocqueville, the tyranny of the majorities. Their fear was directed not so much to the coercive use of the state apparatus, but rather to the coercion of public opinion which, dominated by prejudice and custom, could be clearly intolerant of attitudes or behaviors of a dissident, eccentric or simply different nature. .