The concept of "the absolute" was introduced in modern philosophy, notably by Hegel, for "the sum of all being, actual and potential". For Hegel, states the philosophy scholar Martin Heidegger, the Absolute is "the spirit, that which is present to itself in the certainty of unconditional self-knowing". According to Hegel, states Frederick Copleston – a historian of philosophy, "Logic studies the Absolute 'in itself'; the philosophy of Nature studies the Absolute 'for itself'; and the philosophy of Spirit studies the Absolute 'in and for itself'. The concept is also found in the works of F. W. J. Schelling, and was anticipated by Johann Gottlieb Fichte. In English philosophy, F. H. Bradley has distinguished the concept of Absolute from God, while Josiah Royce, the founder of American idealism school of philosophy, has equated them.