Full Idea
Any counterfactual about a particular event implies or presupposes something about the event's essence.
Gist of Idea
A counterfactual about an event implies something about the event's essence
Source
Jonathan Bennett (Event Causation: counterfactual analysis [1987], p.219)
Book Reference
'Causation', ed/tr. Sosa,E. /Tooley,M. [OUP 1993], p.219
A Reaction
This is where the counterfactual theory suddenly becomes more interesting, instead of just being a rather bare account of the logical structure of causation. (Bennett offers some discussion of possible essential implications).