At the heart of Buddhist ethics is an understanding that whatever we do to hurt others, harms ourselves even more. Hurting others is comparable to throwing burning coals at them – maybe they will be effected by the coal and will get burned, but you yourself are sure to get burned when you pick it up to throw it.
This kind of thinking is fundamentally different from the ethical considerations most of us usually make. Normally we consider ethics to be something that primarily relates to our action’s impact on others. In Buddhism, the starting point of our actions has an impact on ourselves. We carry all our thoughts, our words and deeds with us in life: we call it our karma. Buddhist ethics, which are based on the idea of karma, are not a system of punishment and reward; it is about awareness. If we truly realize that by harming others we first harm ourselves, it will be far easier to act sincerely friendly and compassionate. It is not something we do because we are told to, or something we do because we fear punishment from the outside, it is something we do because we choose not to create causes – karma – that we will have to live on with.