This principle of sympathy is of so powerful and insinuating a nature, that it enters into most of our sentiments and passions, and often takes place under the appearance of its contrary.  For it is remarkable, that when a person opposes me in any thing, which I am strongly bent upon, and rouzes up my passion by contradiction, I have always a degree of sympathy with him, nor does my commotion proceed from any other origin.  We may here observe an evident conflict or rencounter of opposite principles and passions.  On the one side there is that passion or sentiment, which is natural to me; and it is observable, that the stronger this passion is, the greater is the commotion.  There must also be some passion or sentiment on the other side; and this passion can proceed from nothing but sympathy.  The sentiments of others can never affect us, but by becoming, in some measure, our own; in which case they operate upon us, by opposing and encreasing our passions, in the very same manner, as if they had been originally derived from our own temper and disposition.  While they remain concealed in the minds of others, they can never have an influence upon us:  And even when they are known, if they went no farther than the imagination, or conception; that faculty is so accustomed to objects of every different kind, that a mere idea, though contrary to our sentiments and inclinations, would never alone be able to affect us.

The second principle I shall take notice of is that of comparison, or the variation of our judgments concerning ob jects, according to the proportion they bear to those with which we compare them.  We judge more, of objects by comparison, than by their intrinsic worth and value; and regard every thing as mean, when set in opposition to what is superior of the same kind.  But no comparison is more obvious than that with ourselves; and hence it is that on all occasions it takes place, and mixes with most of our passions.  This kind of comparison is directly contrary to sympathy in its operation, as we have observed in treating of com passion and malice. [Book II.  Part II.  Sect.  VIII.] In all kinds of comparison an object makes us always receive from another, to which it is compared, A sensation contrary to what arises from itself in its direct and immediate survey.  The direct survey of another’s pleasure naturally gives us pleasure; and therefore produces pain, when COMPARed with our own.  His pain, considered in itself, is pain FUL; but augments the idea of our own happiness, and gives us pleasure.