Full Idea
Once we conceded that Tom can walk slowly or quickly, and that the slowness and quickness is a property of the walking and not of Tom, we can hardly refrain from quantifying over events (such as 'a walking') in our ontology.
Gist of Idea
If slowness is a property of walking rather than the walker, we must allow that events exist
Source
José A. Benardete (Metaphysics: the logical approach [1989], Ch. 6)
Book Reference
Benardete,José A.: 'Metaphysics: The Logical Approach' [OUP 1989], p.36