So I look at from a historical perspective(surprise). I'm of the belief that all morality began as simple survival. Once upon a time, in the long, long ago, all humans lived in tribes. These tribes had a hierarchical structure with a leader at top. This leader was generally the strongest, most fit male. And more often than not, in this tale, he became leader by way of disposing of the former leader. And this continued. The strong would overpower the weak, the weak would die, then the strong would in turn become weak himself. Until, one day, a wise, or perhaps an evil, leader came to power. He rose as all before him had, but, he saw that fact. And, being a creature endowed with the instict for self preservation, he devised a plan. He spoke to his tribes young men. The young men that he knew would grow to one day overtake him. And he said " yes, leaders can be killed, and their power taken, but, I must tell you of the terrible fate that awaits those that would dare kill a KING. For, of course it is just and sometimes needed to end your enemy, if you strike down your leader, then, when that fate is visited upon you in turn, you suffer not just the pain of the death. No. You continue on, out of your meat prison, to face the eternal and everlasting pain and torture of those whom you have killed to gain power. All the ancestors who ruled and were overthrown by murder await your eternal "soul" so that they might cast upon you unimaginable suffering. The only way to prevent this most terrible of fates, of course, is to not overthrow the KING. If he is allowed to lead until he dies of age in his sleep, his powerful spirit shall not seek yours out for everlasting damnation. So I say unto you, young men of my tribe, guard my life with your own so that once you die of age or injury, you may enjoy the peaceful slumber that awaits."