Full Idea
Newton's First Law of Motion tells us what happens to a body which is not acted upon by a force. Yet it may be that the antecedent of the law is never instantiated. It may be that every body that there is, is acted upon by some force.
Gist of Idea
Newton's First Law refers to bodies not acted upon by a force, but there may be no such body
Source
David M. Armstrong (What is a Law of Nature? [1983], 02.7)
Book Reference
Armstrong,D.M.: 'What is a Law of Nature?' [CUP 1985], p.21