A study in early medieval mereology: Boethius, Abelard, and pseudo-Joscelin
The twelfth-century philosopher Peter Abelard makes the bold claim that no thing
can ever gain or lose a part. This has the remarkable consequence that should, for example, the broom that is in my closet lose a hair, that very broom would no longer exist. This remarkable consequence has prompted many commentators, both medieval and contemporary, to suggest that Abelard has made a serious mistake