 According to the way of example, it suffices to list paradigm cases of abstract and concrete entities in the hope that the sense of the distinction will somehow emerge. Clearly, a list of examples for each category would be a heuristically promising start in the search for some criterion (or list of criteria) that would be fruitful for drawing the distinction. However, a simple list would be of limited significance since there are too many ways of extrapolating from the paradigm cases to a distinction that would cover the unclear cases, with the result that no clear notion has been explained.