Hierocles was a Stoic philosopher. I think his "circles of concern" idea is beautiful, and it perfectly expresses how we should treat one another: treat your neighbours and close friends like family members, treat your countrymen and fellow citizens like your neighbours, treat other members of the human race like fellow citizens and countrymen...

I think the Stoic philosophy has been hijacked somewhat by people who think of it as nothing more than "don't show emotion; be impassive and aloof." But I think Stoic philosophy inherently embodies universal love, which seems to be in short supply these days. Not everyone is our enemy.