“[A] full grown horse or dog is beyond comparison a more rational, as well as a more conversable animal, than an infant of a day, a week, or even a month old. But suppose the case were otherwise, what would it avail? The question is not ‘Can they reason?’ nor ‘Can they talk?’ but ‘Can they suffer?’”

— Jeremy Bentham, Introduction to the Principles of Morals and Legislation (1789)