responsible for "the pleasure of study": (1) Intellectual challenge: the exercise must force us to "fix our attention and exert our genius". (2) Importance/utility: the topic must be useful or important enough to "fix our attention" via "a remote sympathy" with those our work might help (a sympathy that even motivates scholars lacking in "public spirit"). (3) Direct concern: just as hunters and gamblers begin to care about success itself more than the reward it brings, likewise scholars begin to develop a direct concern for the scholarly problems they work on (this due to the aforementioned principle of a "parallel direction"). Finally, Hume offers an account of the social curiosity that fuels gossip: since doubt and uncertainty are painful, especially when they concern events whose ideas are forceful, we are naturally curious about the happenings of our immediate social environment. Book 3: Of Morals Part 1: Of virtue and vice in general Hume begins Book 3 by examining the nature of moral evaluation, offering a critique of moral rationalism and a defense of moral sentimentalism: in the terms of his overall system, Hume is arguing that the evaluations in our mind are impressions, not ideas. His main target is the rationalism of such philosophers as Clarke and Balguy, which posits "eternal fitnesses and unfitnesses of things, which are the same to every rational being that considers them", in effect classifying morality alongside mathematics under "relations of ideas". Hume's principal arguments against this rationalism rest on Book 2's thesis that there is no opposition between reason and the passions: reason alone cannot motivate us, and "passions, volitions, and actions" cannot be in agreement or disagreement with reason. This thesis "proves directly", he writes, that an action's moral status cannot consist in the action's agreement or disagreement with reason, and it "proves indirectly" that moral evaluation, which has a practical influence on us and can "excite passion[s] and produce or prevent actions", cannot be "the offspring of reason". Nor can the morality of an action be founded on the true or false judgements causally linked to it: no immoral action is wrong due to its arising from a mistake of fact, or (contra Wollaston) due to its causing false judgements in others. After summing up this critique, Hume develops a "more particular" case against rationalism, recalling his system's two kinds of reasoning: "the comparing of ideas" and "the inferring of matter of