"I have from an early age abjured the use of meat, and the time will come when men such as I will look upon the murder of animals as they now look upon the murder of men."
This quote, attributed to engineer, artist, musician, and scientist Leonardo da Vinci, expresses perhaps the soul of animal rights philosophy, according to which killing animals for food, clothing, or experiments is equivalent to murdering humans for any purpose other than self-defense or mercy killing. The vision of animal rights held by the People for the Ethical Treatment of Animals (PETA) dictates that humans allow other-than-human species the freedom we desire for ourselves, intervening only to relieve animals from suffering, as when one euthanizes a companion dog riddled with cancer or painful arthritis. When an animal is too sick to find further enjoyment in life, we would sanction the mercy killing of that animal.
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