Nagel has argued that the ‘mind-body’ problem, as traditionally conceived, is insoluble. His challenge to philosophers is to devise a metaphysical scheme that incorporates materialist concepts in describing first person experience and mentalistic concepts in describing third person experience, such that the internal relations between the concepts thereby constructed are necessary. Nagel's own suggestion, a scheme not unlike the ‘underlying process’ schemes of the physical sciences, seems to lead him towards a covert materialism. Progress can be made in meeting the challenge by tackling the problem first by taking the units in each ‘sphere’ to be brains and persons. I show that a metaphysics based on the metaphor of person defined tasks and materially defined tools does satisfy both Nagel's challenge conditions. To devise a scheme for qualia and brain-states I turn back to Locke's presentation of the primary/secondary quality distinction. This depends on the concept of a causal power, grounded in material states of the world. While this scheme is inadequate, a variation, based on Gibson's concept of an affordance, and drawing on Bohr's resolution of the seeming incompatibility between wave and particle ontologies for physics, is promising. The world, whatever it is, affords material states to our perceptual apparatus, and mental states to our proprioceptual apparatus. The mental states/brain states duality is not a duality of types of states, which might stand in causal relations to one another, but is a duality of means of access to two classes of affordances of whatever the world is. There is no mind-body problem in the traditional sense, namely ‘How could a material state cause or be caused by a mental state?’