This is one of the twenty-three lectures on the Principles of Surgery delivered by John Hunter in 1786. Only those portions of the lecture which deal with the use of rest and motion are reprinted. The full lecture will be found in The Complete Works of John Hunter, F.R.S., edited by James F. Palmer, published at Philadelphia in 1841 by Haswell, Barring ton and Haswell; volume I, page 267.