Just as the Bible teaches the Golden Rule - "Do unto others as you would have others do unto you” - the Mahabharata (5.39.57), predating the Bible, teaches a similar truth, and in almost the exact same wording. Yogis and spiritual adepts in India extend the teaching to its logical limits, showing kindness to all species of life - and this, of course, means vegetarianism. It is hard to be kind to animals if you are eating them. In other words, if you don't want someone eating your entrails, don't eat the entrails of others.