But so far from there being an alliance between ethicks and physics, nearly all Nature’s works are at war with each other, the good of the one being … - Lewis Gompertz

Can a reflecting mind turn for a moment to any quarter without shrinking at the scenes of carnage and suffering which constitute not only the minor streams, but the grand tide of life: though mingled with many pleasures we admit; but the goods falling mostly on man, and the evils mostly on animals. Those men, however, who are above others, and still more above dumb animals in happiness, are readily led to believe that the sweets of life greatly predominate in the whole classes of animated beings, yet an impartial view seems to tell a very different tale.

Y: Do you include those animals which are guilty of the same crime themselves by living on prey? Should we not then save a thousand lives by killing one?
Z: We must never suppose a person or an animal guilty until they are found in the act, and then we must investigate the nature of the crime. It is true that the animal living by slaughter may be less entitled to our consideration than the animal which is harmless; but recollect, the former may plead the same excuse itself, unless his slaughter be only of those animals which live on vegetables; and then, though justice may require their destruction, it would be repugnant to the feelings of humanity to slaughter them with that plea, unless we could quite assure our conscience that our design in killing them was more to prevent their doing mischief than for our own benefit: besides, we might then extend this principle still further, and kill our own species because they are also animals of prey. It is moreover to be observed, that if one carnivorous animal kills another, he may save lives by it also, and the nature of the act will be different according to circumstances [...] And, further, it will frequently be impossible to discover when the animal becomes guilty or innocent, as it depends on such a variety of circumstances: we should therefore be more safe from infringing the laws of moral rectitude, not to interfere in this case.

Suppose...we reflect on the building of London Bridge, we cannot then help admiring the genius and assiduity of man. But could all the torture and destruction that this has caused to the poor horses, who drew the stones and cleared the rubbish, be brought to light, what an emblem of crime would this beautiful bridge exhibit; many years’ labour has it cost; many teams have been constantly at work, and the extreme severity of the labour imposed on them was almost at any time to be seen. Now, if all the strainings, the lashes, the blows, and the wrenchings with all the bits, had been kept account of, how immense would be the list...