Full Idea
A body is said to work upon or act, that is to say, do something to another body, when it either generates or destroys some accident in it.
Gist of Idea
Acting on a body is either creating or destroying a property in it
Source
Thomas Hobbes (De Corpore (Elements, First Section) [1655], 2.09.01)
Book Reference
Hobbes,Thomas: 'Metaphysical Writings', ed/tr. Calkins,Mary Whiton [Open Court 1905], p.69