Full Idea
The explanation of material constitution given by substance essentialism is that there are multiple objects. A person is essentially human-shaped (falling under the human sort), while their hunk of tissue is accidentally human-shaped (as tissue).
Gist of Idea
Substance essentialism says an object is multiple, as falling under various different sortals
Source
L.A. Paul (In Defense of Essentialism [2006], §1)
Book Reference
'Metaphysics (Philosophical Perspectives 20)', ed/tr. Hawthorne,John [Blackwell 2006], p.341
A Reaction
At this point sortal essentialism begins to look crazy. Persons are dubious examples (with sneaky dualism involved). A bronze statue is essentially harder to dent than a clay one, because of its bronze. If you remake it of clay, it isn't the same statue.
Related Idea
Idea 14193 'Substance theorists' take modal properties as primitive, without structure, just falling under a sortal [Paul,LA]