The analysis of mental concepts suggests that the distinctionbetween the mental and the nonmental is not ontologically fundamental,and that, whereas mental processes are one and the same things as thebrain processes with which they are correlated, dispositional mentalstates depend causally on and are, thus, ''''distinct existences'''' fromthe states of the brain microstructure with which ''they'' are correlated.It is argued that this difference in the relation between an entity andits composition/underlying structure applies across the board. allstuffs and processes are the same thing as is described by a descriptionof their microstructure. In all cases where the manifestation of adisposition extends beyond the ''''skin'''' of the dispositional propertybearer, dispositions invariably depend causally on the structure,usually the microstructure, of the bearer.