Proof.- Mirth (see its Def. in III:xi.Note) is pleasure. which, in so far as it is referred to the body, consists in all parts of the body being affected equally: that is (III:xi.), the body's power of activity is increased or aided in such a manner, that the several parts maintain their former proportion of motion and rest; therefore Mirth is always good (IV. xxxix.), and cannot be excessive. But Melancholy (see its Def. in the same note to III:xi.Note) is pain, which, in so far as it is referred to the body, consists in the absolute decrease or hindrance of the body's power of activity; therefore (IV:xxxviii.) it is always bad. Q.E.D.
Prop. XLIII. Stimulation may be excessive and bad; on the other hand, grief may be good, in so far as stimulation or pleasure is bad.
Proof.- Localized pleasure or stimulation (titillatio) is pleasure, which, in so far as it is referred to the body, consists in one or some of its parts being affected more than the rest (see its Definition, III:xi.Note); the power of this emotion may be sufficient to overcome other actions of the body (IV:vi.), and may remain obstinately fixed therein, thus rendering it incapable of being affected in a variety of other ways: therefore (IV:xxxviii.) it may be bad. Again, grief, which is pain, cannot as such be good (IV:xli.). But, as its force and increase is defined by the power of an external cause compared with our own (IV:v.), we can conceive infinite degrees and modes of strength in this emotion (IV:iii.); we can, therefore, conceive it as capable of restraining stimulation, and preventing its becoming excessive, and hindering the body's capabilities; thus, to this extent, it will be good. Q.E.D.
Prop. XLIV. Love and desire may be excessive.
Proof.- Love is pleasure, accompanied by the idea of an external cause (Def_of_Emotions:vi.); therefore stimulation, accompanied by the idea of an external cause is love (III:xi.Note); hence love maybe excessive.
Again, the strength of desire varies in proportion to the emotion from which it arises (III:xxxvii.). Now emotion may overcome all the rest of men's actions (IV:vi.); so, therefore, can desire, which arises from the same emotion, overcome all other desires, and become excessive, as we showed in the last proposition concerning stimulation.
Note.- Mirth, which I have stated to be good, can be conceived more easily than it can be observed. For the emotions, whereby we are daily assailed, are generally referred to some part of the body which is affected more than the rest; hence the emotions are generally excessive, and so fix the mind in the contemplation of one object, that it is unable to think of others; and although men, as a rule, are a prey to many emotions - and very few are found who are always assailed by one and the same - yet there are cases, where one and the same emotion remains obstinately fixed. We sometimes see men so absorbed in one object, that, although it be not present, they think they have it before them; when this is the case with a man who is not asleep, we say he is delirious or mad; nor are those persons who are inflamed with love, and who dream all night and all day about nothing but their mistress, or some woman, considered as less mad, for they are made objects of ridicule. But when a miser thinks of nothing but gain or money, or when an ambitious man thinks of nothing but glory, they are not reckoned to be mad, because they are generally harmful, and are thought worthy of being hated. But, in reality, Avarice, Ambition, Lust, &c., are species of madness, though they may not be reckoned among diseases.
Prop. XLV. Hatred can never be good.
Proof.- When we hate a man, we endeavour to destroy him (III.xxxix.), that is (IV:xxxvii.), we endeavour to do something that is bad. Therefore, &c. Q.E.D.
N.B. Here, and in what follows, I mean by hatred only hatred towards men.
Corollary I.- Envy, derision, contempt, anger, revenge, and other emotions attributable to hatred, or arising therefrom, are bad; this is evident from III:xxxix. and IV:xxxvii.
Corollary II.- Whatsoever we desire from motives of hatred is base, and in a State unjust. This also is evident from III:xxxix., and from the definitions of baseness and injustice in IV:xxxvii.Note.
