Full Idea
Events are widely acknowledged to be particulars, but they are plainly not ordinary concrete particulars. They are best viewed as trope-sequences, in which one condition gives way to another. They are changes in which tropes replace one another.
Gist of Idea
Events are trope-sequences, in which tropes replace one another
Source
Keith Campbell (The Metaphysic of Abstract Particulars [1981], §3)
Book Reference
'Properties', ed/tr. Mellor,D.H. /Oliver,A [OUP 1997], p.129
A Reaction
If nothing exists except bundles of tropes, it is worth asking WHY one trope would replace another. Some tropes are active (i.e. they are best described as 'powers').