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come now to the examination of such virtues and vices as are entirely natural, and have no dependence on the artifice and contrivance of men. The examination of these will conclude this system of morals.

The chief spring or actuating principle of the human mind is pleasure or pain; and when these sensations are remov'd, both from our thought and feeling, we are, in a great measure, incapable of passion or action, of desire or volition. The most immediate effects of pleasure and pain are the propense and averse motions of the mind; which are diversified into volition, into desire and aversion, grief and joy, hope and fear, according as the pleasure or pain changes its situation, and becomes probable or improbable, certain or uncertain, or is consider'd as out of our power for the present moment. But when along with this, the objects, that cause pleasure or pain, acquire a relation to ourselves or others; they still continue to excite desire and aversion, grief and joy: But cause, at the same time, the indirect passions of pride or humility, love or hatred, which in this case have a double relation of impressions and ideas to the pain or pleasure.

We have already observ'd, that moral distinctions depend entirely on certain peculiar sentiments of pain and pleasure, and that whatever mental quality in ourselves or others gives