Abstract
Statistical mechanics has two foundations; first, the early attempts from the late 17th century onwards to explain the bulk properties of matter in terms of the forces between the constituent particles, and secondly, the attempts in the early 19th century to explain the properties of gases in terms of the rapid motion of free particles. The combination of these two approaches was a task of the late 19th and early 20th centuries. The advent of quantum theory clarified many of the difficulties and showed how appropriate was Willard Gibbs's treatment of the subject. The paper shows how modern work has evolved from these foundations.
Acknowledgements
I thank my colleague David Logan for his comments on an early draft of this paper and a referee for the quotation in reference 13.