Full Idea
Sortals are the terms by which we intend to classify physical objects according to the nature and origin of their unity.
Gist of Idea
We use sortals to classify physical objects by the nature and origin of their unity
Source
M.R. Ayers (Individuals without Sortals [1974], 'Concl')
Book Reference
-: 'Canadian Journal of Philosophy' [-], p.146
A Reaction
This is as opposed to using sortals for the initial individuation. I take the perception of the unity to come first, so resemblance must be mentioned, though it can be an underlying (essentialist) resemblance.