Full Idea
We cannot say that a particle is composed entirely of its several universals, because then another particle exactly like it would have the very same universals, and yet the two particles would not be the same.
Gist of Idea
If particles were just made of universals, similar particles would be the same particle
Source
David Lewis (On the Plurality of Worlds [1986], 1.5)
Book Reference
Lewis,David: 'On the Plurality of Worlds' [Blackwell 2001], p.65
A Reaction
This is an argument either (implausibly) for haecceities or characterless substrata, or else for tropes (which are all separate, unlike universals). Particles as bundles of universals is not a theory I take seriously.