1. To what part of our nature do pleasure and grief, fear and
boldness desire and aversion, and, last, pain, belong? Is it to
the soul (herself),[271] or to the soul when she uses the body as an
instrument,[272] or to some third (combination) of both? Even the
latter might be conceived of in a double sense: it might be either
the simple mixture of the soul and the body,[273] or some different
product resulting therefrom.[274] The same uncertainty obtains
about the products of the above mentioned experiences: namely,
passions,[275] actions, and opinions. For example, we may ask whether
ratiocination[276] and opinion both, belong to the same principle as
the passions; or whether only one of them does; in which case the
other would belong to some other principle. We should also inquire
concerning the nature and classification of thought.[277] Last we
should study the principle that undertakes this inquiry and which comes
to some conclusion about it. But, first of all, who is the agent, who
feels? This is the real starting point: for even passions are modes of
feeling, or at least they do not exist without it.[278]