Michele Federico Sciacca was a founder of the Gallarate movement, professor of theoretical philosophy at the University of Genoa, and the founder and editor of the journals Giornale di metafisica and Humanitas. He started as a historian of ideas, writing important works on Reid (1935), Plato (1939), and St. Augustine (1939); a massive review of Italian thought, Il XX secolo (2 vols., Milan, 1941); and a review of contemporary European thought, La filosofia oggi (Milan, 1945).

Although Sciacca studied under Antonio Aliotta, his major stimulus came from Giovanni Gentile, from whom Sciacca derived his basic axiom that concrete being must be act, never fact. Sciacca developed this principle in his own fashion under the influence of Plato, St. Augustine, Antonio Rosmini-Serbati, and Maurice Blondel.

Sciacca's position was one of "integralism." The central notion of integralism is interiority, according to which the ground of all forms of being and...