6. It is rare that a passion arises and develops without obstacles and resistance. Hence that state we have called _fluctuation_ (Vol. I., p. 167), and which has so often been compared to the ebb and flow of the sea. These general features of the passions being stated, let us make a brief sketch of the principal passions. It may be said that our passions pass through three distinct states; they are at first natural and unavoidable affections of the mind: _inclinations_, _tendencies_; they become next violent and unruly movements: these are the passions properly so-called; they become habits and embodied in the character, and take the name of _qualities_ and _defects_, _virtues_ and _vices_. But it is to be noted that whilst we can always distinguish these three states theoretically, language is, for the most part, inadequate to express them; for men have designated these moral states only according to the necessities of practice, and not according to the rules of theory. The three states which we have just pointed out, can be very clearly distinguished in the first of the affections of human nature, namely, the _instinct of self-preservation_. This instinct is at first a natural, legitimate, necessary affection of the human heart; but by the force of circumstances, the influence of age, disease, temperament, it develops out of proportion into a state of passion, and becomes what we call _fear_; or else it turns into a habit and becomes the vice we call _cowardice_. Physical self-preservation is inseparable from two _appetites_ called hunger and thirst. These two appetites, too much indulged in, become passions, which themselves may become vices. But language fails here to express their various shades: there is only one word to express the passion or vice related to eating and drinking: it is on the one hand _gluttony_, and on the other _drunkenness_;[156] both these vices, and in general all undue surrender to sensual pleasures, is called _intemperance_. The source of all our personal inclinations is the love for ourselves or _self-love_, a legitimate instinct when kept within bounds; but when carried to excess, when exclusive and predominant, it becomes the vice we call _selfishness_. Self-esteem, developed into a passion, becomes, when it turns upon great things, _false pride_; when upon small, _vanity_. _The love of liberty_ degenerates into a _spirit of revolt_; the legitimate love of power, into _ambition_; _the instinct of property_ becomes _greed_, _cupidity_, _passion for gain_, and tends to run into the _passion for gambling_ or the desire to gain by means of chance. The desire for gain engenders the _fear of loss_, and this latter passion developing into a vice and mania, becomes _avarice_. Human inclinations are divided into _benevolent_ and _malevolent_ inclinations. The first may develop into a passion, but not into a vice; the second alone become vices.