This is very similar to Aristotle's views on friendship in Nichomachean Ethics.
He has a final category of 'true friend' that refer to someone who reflects part of your being back at you. Given that this is possible with another person he is able to resolve the question of "why should we behave morally?" by pointing out that every other human is potentially a true friend who may instantiate an aspect of you. In this case acting without considering the interests of others is acting against your own interests.
He has a final category of 'true friend' that refer to someone who reflects part of your being back at you. Given that this is possible with another person he is able to resolve the question of "why should we behave morally?" by pointing out that every other human is potentially a true friend who may instantiate an aspect of you. In this case acting without considering the interests of others is acting against your own interests.