 which can be a source of happiness, originates in the natural feelings which makes us share the sorrow of all sentient beings. Preserve it in all its purity and all its strength. Do not limit it to the suffering of men, but extend your humanity even to animals. Do not make any which belong to you unhappy; do not neglect their welfare; do not be insensitive to their naïve and sincere gratitude; cause them no unnecessary pain. Anything of the sort would be a true injustice and an insult to nature, who would punish you by the hardness of heart which habitual cruelty must produce. Lack of foresight in animals is the only excuse for the barbarous law which condemns them to serve as food for one another. Let us remain faithful to nature, and go no further than this excuse permits. (McLean and Hewitt 1994, 287)