 The matter is not so simple, however. It is possible, and not uncommon, for concepts of a certain kind to be exemplified, but for it to be the case that, nevertheless, entities answering directly to those concepts are not included in the most economical statement of one’s ontology. This is reductionism, and it can operate in either of two ways, namely either analytical reductionism or what one might call de facto or ‘nothing but’ reductionism. In the present case, it would conform to the analytical option if the concept of substance could be analysed in terms of properties or events (e.g., ‘to be a substance =df to be a collection of properties bound together in way W’). But one might still hold that, though the concept of substance is not precisely analysable and is indispensable, substances in fact are nothing but collections of properties. This latter is the de facto option. So the existence of substances does not show that the concept is important from a philosophical perspective, or, if it has some significance, whether this is just as a necessary part of our conceptual scheme, or as an ineliminable feature of reality itself.