Desires, which follow from our nature in such a manner, that they can be understood through it alone, are those which are referred to the mind, in so far as the latter is conceived to consist of adequate ideas: the remaining desires are only referred to the mind, in so far as it conceives things inadequately, and their force and increase are generally defined not by the power of man, but by the power of things external to us: wherefore the former are rightly called actions, the latter passions, for the former always indicate our power, the latter, on the other hand, show our infirmity and fragmentary knowledge.