 Neutral monism and the dual-aspect theory share a central claim: there is an underlying reality that is neither mental nor physical. But that is where the agreement stops. Neutral monism has no room for the central feature of the dual-aspect theory: the mental and physical aspects, or sides, or properties that characterize the underlying entities of dual-aspect theory. The neutral monist accepts the mental/physical distinction. But it resides at the level or groups of neutral entities. Grouped one way, the neutral entities that constitute your brain are thoughts and feelings; grouped another way, they are atoms and neurons and lobes. Whether a given group of interrelated neutral entities counts as mental or physical depends on the functional role this group occupies (see section  3).  On this picture, the mentality and physicality are features of complex structures of neutral entities. But the entities themselves are free of mental or physical aspects/sides/properties. Therein consists their neutrality.