2. The great mark of a passion is its sensible working of itself out upon the body,--what Dr. Bain calls "the diffusive wave of emotion." Without this mark there is no passion, but with it are other mental states besides passions, as we define them. All strong emotion affects the body sensibly, but not all emotions are passions. There are emotions that arise from and appertain to the rational portion of the soul. Such are Surprise, Laughter, Shame. There is no sense of humour in any but rational beings; and though dogs look ashamed and horses betray curiosity, that is only inasmuch as in these higher animals there is something analogous to what is reason in man. Moreover passions are conversant with good and evil affecting sense, but the objects of such emotions as those just mentioned are not good and evil as such, common parlance notwithstanding, whereby we are said to laugh at a _bon mot_, or "a good thing." 3. _Love_ is a generic passion, having for its species _desire_ and _delight_, the contraries of which are _abhorrence_ and _pain_. Desire is of absent good; abhorrence is of absent evil; delight is in present good; pain is at present evil. The good and the evil which is the object of any passion must be apprehended by sense, or by imagination in a sensible way, whether itself be a thing of sense or not. 4. Desire and abhorrence, delight and pain, are conversant with good and evil simply. But good is often attainable only by an effort, and evil avoidable by an effort. The effort that good costs to attain casts a shade of evil or undesirableness over it: we may shrink from the effort while coveting the good. Again, the fact of evil being at all avoidable is a good thing about such evil. If we call evil black, and good white, avoidable evil will be black just silvering into grey: and arduous good will be white with a cloud on it. And if the white attracts, and the black repels the appetite, it appears that arduous good is somewhat distasteful, to wit, to the faint-hearted; and avoidable, or vincible, evil has its attraction for the man of spirit. About these two objects, good hard of getting and evil hard of avoidance, arise four other passions, hope and despair about the former, fear and daring about the latter. Hope goes out towards a difficult good: despair flies from it, the difficulty here being more repellent than the good is attractive. Fear flies from a threatening evil: while daring goes up to the same, drawn by the likelihood of vanquishing it. _Desire_ and _abhorrence_, _delight_ and _pain_, hope and despair, fear and daring, with anger and hatred (of which presently), complete our list of passions.