Thomas Reid (1710-96) is increasingly being seen as a central figure in the Scottish Enlightenment. His Inquiry into the Human Mind on the Principles of Common Sense has long been recognized as a classic philosophical text. Since its first publication in 1764, no fewer than forty editions have been published. The proliferation of secondary literature further indicates that Reid's work is flourishing as never before, yet there exist thousands of unpublished manuscript pages in Reid's hand, many of which relate directly to the composition of the Inquiry. Furthermore, no account has been taken of the successive alterations made to the four editions published in Reid's lifetime. This new edition, edited by Derek Brookes, aims to present a complete, critically edited text of the Inquiry, accompanied by a judicious selection of manuscript evidence relating to its composition.The volume contains a preface by Brookes followed by an introduction giving the central argument of the Inquiry by means of a historical and philosophical account of its formation. The critical text is based on the fourth lifetime edition (1785), while the textual notes include bibliographical details and allusions, translations, references to secondary literature, and selected passages from Reid's manuscript.