T 2.2.12.6

'Tis evident, that sympathy, or the communication of passions, takes place among animals, no less than among men. Fear, anger, courage and other affections are frequently communicated from one animal to another, without their knowledge of that cause, which produc'd the original passion. Grief likewise is receiv'd by sympathy; and produces almost all the same consequences, and excites the same emotions as in our species. The howlings and lamentations of a dog produce a sensible concern in his fellows. And 'tis remarkable, that tho' almost all animals use in play the same member, and nearly the same action as in fighting; a lion, a tyger, a cat their paws; an ox his horns; a dog his teeth; a horse his heels: Yet they most carefully avoid harming their companion, even tho' they have nothing to fear from his resentment; which is an evident proof of the sense brutes have of each other's pain and pleasure.