Henry Home - better known by his judicial title Lord Kames - was an important figure in enlightenment Scotland. Kames published many books and essays across a variety of fields of knowledge. A substantial number of his publications related to his vocation as an advocate, and later a judge, in Scotland. This paper provides an introduction to Lord Kames' rich legal life, particularly the way it was shaped by his experience as a Scottish lawyer in eighteenth-century Edinburgh. The paper is an introduction to a reprint of the third edition of the Principles of Equity, part of the Old Studies in Scots Law series, published by the Edinburgh Legal Education Trust. One of Kames' most important legal works, the Principles of Equity subsequently achieved status, that is to say it represents a formal source of law in Scotland. The Principles was the first systematic monograph treatment of equity in English, and contains a sophisticated analysis of the interaction of equity and common law in the abstract, and in relation to Scots law particularly. The paper considers Kames' historically informed account of an evolutionary development of equity, and its underlying justificatory premises, as set out in the Principles. The paper considers how lawyers, and others, in both Scotland and America, cited the Principles in reported cases and doctrinal writing, and how Kames' influence can be sketched through his legal and non-legal works. The final section of the paper considers Kames' subsequent reputation, noting the fluctuating respect accorded to Kames' works, including the Principles, by lawyers. The paper concludes that the on-going development of the meaning and relevance of institutional works in Scotland suggests that a renewed interest in Kames' critical approach is possible.