There are many physical and chemical phenomena which, like elective affinities or dissipative chaotic systems, seem to be proto-volitional, so as to suggest that given a physicalist theory of mind it would not be too hard to ensure that desire was also explained via fundamental forces. This is quite wrong because when such phenomena and their characteristic forces are incorporated into a physicalist theory they only act according to cause and effect rules, the thing about them that looks like intentionality is precisely what can't be part of the explanation. Desire leads to an explanatory gap as surely as qualia. In fact it is much easier to see physical forces as primitive forms of desire than the other way around. This is pretty much the 'intrinsic nature' idea of consciousness, or equivalently Schopenhauer's Will.