If the injured should perish in the quarrel, we not only sympathize with the real resentment of his friends and relations, but with the imaginary resentment which in fancy we lend to the dead, who is no longer capable of feeling that or any other human sentiment. But as we put ourselves in his situation, as we enter, as it were, into his body, and in our imaginations, in some measure, animate anew the deformed and mangled carcass of the slain, when we bring home in this manner his case to our own bosoms, we feel upon this, as upon many other occasions, an emotion which the person principally concerned is incapable of feeling, and which yet we feel by an illusive sympathy with him. The sympathetic tears which we shed for that immense and irretrievable loss, which in our fancy he appears to have sustained, seem to be but a small part of the duty which we owe him. The injury which he has suffered demands, we think, a principal part of our attention. We feel that resentment which we imagine he ought to feel, and which he would feel, if in his cold and lifeless body there remained any consciousness of what passes upon earth. His blood, we think, calls aloud for vengeance. The very ashes of the dead seem to be disturbed at the thought that his injuries are to pass unrevenged. The horrors which are supposed to haunt the bed of the murderer, the ghosts which, superstition imagines, rise from their graves to demand vengeance upon those who brought them to an untimely end, all take their origin from this natural sympathy with the imaginary resentment of the slain. And with regard, at least, to this most dreadful of all crimes, Nature, antecedent to all reflections upon the utility of punishment, has in this manner stamped upon the human heart, in the strongest and most indelible characters, an immediate and instinctive approbation of the sacred and necessary law of retaliation.
It's also a nice example of the Smithian way with a phrase; I particularly like the part about our imaginations animating "anew the deformed and mangled carcass of the slain".