There are a few ethical principles that have appeared throughout world cultures and religions, and the ethic of reciprocity, or the Golden Rule (do unto others as you would have them do to you) is one of them. I suppose we can infer that the universality of this ethic suggests that it really is part of what it means to be human. The parable of the Good Samaritan is among the most popular in Christianity. It's a story (very very short!) told by Jesus in a conversation about the admonishment to "love your neighbor as yourself." "But who is my neighbor?" asked his listener.
A man was on the road from Jerusalem to Jericho, a mountain road so steep and dangerous and infested with bandits that it was known as the Bloody Way. This day it matched its reputation. The traveler was attacked and robbed by highwaymen, and left bleeding and unconscious on the side of the road.
Some time later, a priest was traveling the same road, and although he saw the wounded man he did not stop - maybe he thought the victim was beyond help, or maybe he feared it was a trap - whatever he thought, he hurried past. Shortly after that, another man passed as well, but kept to the far side of the road and didn't even check for signs of life. Sad to say, these two men were of the same nationality as the victim, as they knew from their clothing. A man from Samaria, a stranger in these parts, came along the Bloody Way next. Without caring for nationality, without caring if the wounded man was an innocent victim or an evil man done in by his evil comrades, this Samaritan lifted the unconscious traveler onto his own donkey, bound his wounds, and took him to the nearest inn. Leaving money with the innkeeper, the Samaritan promised to be back with more for the care and tending of the victim.
Who is my neighbor? Everyone, according to this story. Humanity calls us act humanely, yet we so often need courage to follow this universal human requirement. It does raise the question: what fears stop us from treating others as we wish to be treated?