Starting out for the southern end of the Reading Viaduct means walking alongside a live railroad track, vigilant for the sound of a CSX freight train approaching from behind. Your destination is the mouth of an abandoned tunnel, which will pull you i…

Philia, the root of Philadelphia, roughly translates to “friendship” in Aristotle’s Nicomachean Ethics, an enduring source for understanding the ethics of friendship. Aristotle identifies three essential bases for friendship: utility, pleasure, and…