The Great Man theory is a 19th-century idea according to which history can be largely explained by the impact of "great men", or heroes; highly influential individuals who, due to either their personal charisma, intelligence, wisdom, or political skill utilized their power in a way that had a decisive historical impact. The theory was popularized in the 1840s by Scottish writer Thomas Carlyle. But in 1860 Herbert Spencer formulated a counter-argument that has remained influential throughout the 20th century to the present: Spencer said that such great men are the products of their societies, and that their actions would be impossible without the social conditions built before their lifetimes.[1][2][3] Thus subsequent social history, economic history, and political history have de-emphasized the primacy of great men.