Said John Stuart Mill: "To draw inferences has been said to be the great business of life.... It is the only occupation in which the mind never ceases to be engaged." If this be so, it seems a pity that Mill did not recognize that this business identifies what we mean when we say "mind." If he had recognized this, he would have cast the weight of his immense influence not only against the conception that mind is a substance, but also against the conception that it is a collection of existential states or attributes without any substance in which to inhere; and he would thereby have done much to free logic from epistemological metaphysics. In any case, an account of intellectual operations and conditions from the standpoint of the rôle played and position occupied by them in the business of drawing inferences is a different sort of thing from an account of them as having an existence _per se_, from treating them as making up some sort of existential material distinct from the _things_ which figure in inference-drawing. This latter type of treatment is that which underlies the psychology which itself has adopted uncritically the remnants of the metaphysics of soul substance: the idea of accidents without the substance.[48] This assumption from metaphysical psychology--the assumption of consciousness as an existent stuff or existent process--is then carried over into an examination of knowledge, so as to make the theory of knowledge not logic (an account of the ways in which valid inferences or conclusions from things to other things are made), but epistemology.