The philosophical writings of Lady Mary Shepherd (1777–1847) reveal an astute and lively intellect. In An Essay upon the Relation of Cause and Effect (1824) and Essays on the Perception of an External Universe, and Other Subjects Connected with the Doctrine of Causation (1827), Shepherd engaged critically with the views of Hume, Berkeley, Reid, Stewart, de Condillac, and others, but she also presented an original and carefully argued philosophical system of her own. Highly regarded in her day, Shepherd's work faded into obscurity after her death; this collection of selections from her writings is intended to bring her work back into focus for students and scholars. Selections include her writings about causation, knowledge of the external world, mathematical and physical induction, belief in miracles and God, and mind and body. This volume also includes an 1828 essay Shepherd published on vision.