I don’t understand it. I try to wrap my head around it, try writing words on paper and connecting them to each other in webs to see why, how people are different. I know that we are made to see differences — it’s what keeps us alive. Differences are why our ancestors were able to tell the good, red berries apart from the poisonous, pinker ones and live on and on to make us. It’s why using highlighters while studying makes us perceive the yellowed lines as distinguished, set apart, important. But when it comes to people, what compels some differences to make us want to scoot closer to those similar to us? What role does the external occupy to make us forget that, just a few millimeters deeper than the space of skin color, we are remarkably the same?

I thought about this a lot while traveling in Poland with Stanford Hillel, on this inaugural trip for Jewish and non-Jewish students (like myself) alike. This idea kept running through my mind, sprinting, because after seeing Auschwitz in person, there had to be something Nazi soldiers told themselves as they killed six million people. How did perceived differences inform the eugenics that charged their speeches, the “logical” justifications they preached? Maybe they just focused on the numbers — maybe to them, they killed just six million, not six million people. But still the question remains: How do people go about distancing other people from their humanity?

More hauntingly: In the occasional swastika found graffitied on campus, why does this keep coming up?

Time and time again on the trip, we talked about the mobility of narratives and how they can compete, overpower each other and fade back away. Warsaw, Poland’s capital, saw 90 percent of its city destroyed during World War II — rubble piled where buildings once towered, brokenness in its people and architecture. In its loud silence, the once dynamic capital spoke the story of a shattered landscape. Today, however, it’s a sprawling, neon-lit hub alive with its embodiment of the new. Destruction has forced Warsaw forward. As much as it is a place whose founding dates back to 1200, its modernity — shopping malls and Ubers and all — remind me more of my hometown Los Angeles than of an ancient city.

This renewal of architecture (and of culture, really) parallels something I read a few years ago. In 2007, NPR reported that our bodies replace 98 percent of our atoms every year. “These atomic makeovers prompt a more philosophical question,” David Kestenbaum wrote. “Are people really themselves if their atoms are always new, or are they new people each year?” It’s amazing how something as abstract as “what we are” is defined by something so physical, then perhaps re-defined once the body hits “refresh.” If we shed our components annually, our particles and sub-particles, then what are we after the fact? What are we then, when the carbons in our cyclohexanes renew — what’s left but our memories?

It reminds me of Warsaw, because it makes me wonder what remains of its past when so much of it is burned and buried. Our tour guide made a point of answering this question in one of our many walks around the city. Much of Warsaw is built on mounds, marked by the lack of ground floors in some buildings. The landscape was made uneven by what lies underneath. The new city is built atop the old one in a literal sense — atop the war-torn schools and post offices and people. Some people claim to feel it in their bones, the dead underneath who were not put to rest properly — ironically for Poland, a country whose name means “rest here.”

When everything around us has changed — changed with the times, or with war, or with a new president — the last text at the Auschwitz-Birkenau Memorial and Museum rings even more true: “It happened, therefore it can happen again: This is the core of what we have to say.” This is easiest to forget when it’s most important to remember.

Contact Amanda Rizkalla at amariz ‘at’ stanford.edu.