form an idea of the other. This brings us to the third and final stage of Hume's account, our belief in the other object as we conclude the process of probable reasoning (e.g., seeing wolf tracks and concluding confidently that they were caused by wolves). On his account of belief, the only difference between a believed idea and a merely conceived idea lies in the belief's additional force and vivacity. And there is a general psychological tendency for any lively perception to transfer some of its force and vivacity to any other perception naturally related to it (e.g., seeing "the picture of an absent friend" makes our idea of the friend more lively, by the natural relation of resemblance). Thus in probable reasoning, on Hume's account, our lively perception of the one object not only leads us to form a mere idea of the other object, but enlivens that idea into a full-fledged belief. (This is only the simplest case: Hume also intends his account to explain probable reasoning without conscious reflection as well as probable reasoning based on only one observation.) Sections 9–13 Hume now pauses for a more general examination of the psychology of belief. The other two natural relations (resemblance and contiguity) are too "feeble and uncertain" to bring about belief on their own, but they can still have a significant influence: their presence strengthens our preexisting convictions, they bias us in favor of causes that resemble their effects, and their absence explains why so many don't "really believe" in an afterlife. Similarly, other kinds of custom-based conditioning (e.g., rote learning, repeated lying) can induce strong beliefs. Next, Hume considers the mutual influence of reasoning and the passions, and of belief and the imagination. Only beliefs can have motivational influence: it is the additional force and vivacity of a belief (as opposed to a mere idea) that makes it "able to operate on the will and passions". And in turn we tend to favor beliefs that flatter our passions. Likewise, a story must be somewhat realistic or familiar to please the imagination, and an overactive imagination can result in delusional belief. Hume sees these diverse phenomena as confirming his "force and vivacity" account of belief. Indeed, we keep ourselves "from augmenting our belief upon every increase of the force and vivacity of our ideas" only by soberly reflecting on past experience and forming "general rules" for ourselves.