There’s a fascinating and, to the best of my understanding, ongoing debate regarding the philosophical questions, “what is the self?” and “does it even exist?”

I’m not going to wade into those heady waters right now^[1], instead opting for a tangential discussion; a romantic walk on the beach.

Assuming that some flavor of “the self” does exist, another conundrum that directly follows is: “where is it?”

“Where does you or me start and end?”

I’m not offering any definitive answers, but leftovers and engineering are two topics that have something to add to our sandy, barefoot escapade.

I’d wager everyone reading has dealt with and scorned stained Tupperware, leftover, or take-out containers at some point. Chili, curry, spaghetti, or mold so old it’s jaded and entering its supervillain era, actively plotting world domination by disrupting global penicillin supply. Bam.

Now, the exact mechanism of why plastic containers get stained is not critical^[2]. What is critical is that you and me; we’re the chili absorbing, cheap plastic containers. Before expanding on that irksome nugget, a small engineering lesson.

System definitions are about as foundational a concept as you’ll find in engineering. How you define a system dictates nearly everything about its analysis and resulting solutions.

The aspect we’re most interested in is open and closed systems.

• Open systems involve transfer of both mass and energy across the chosen system boundary. That is, both stuff and energy cross the boundaries of “inside” and “outside” the system.
• In contrast, closed systems allow energy, but not mass, to transfer in and/or out.

So, consider a glass of refreshing, cold water on a table. Let’s designate our system boundary as “the glass plus the water inside it.” That’s an open system. It can both warm to room temperature (energy transfer) and can evaporate into the surrounding room (mass transfer), which is outside our boundary condition. Slap that same water in a sealed aluminum can, and now it’s a closed system. It will still warm to room temperature, but no mass will transfer across our chosen boundary. Lastly, pop the tab and we’ve gone from closed to open.

Some other examples of open systems: your car consuming fuel and releasing CO², us humans, and a campfire. For closed systems: refrigerators, planet Earth inside our cozy atmospheric shell, and the soda cooler at a party next to the one with the beer.

Taking a closer look at us humans and the aforementioned containers of chili; it’s obvious that we exist almost exclusively in an open-system context. And the sealed container of leftovers is closed, both colloquially and engineeringly. Further, it’s trivial to see how the chili container goes from closed to open when it’s about to be eaten.

And yet, what about “the self?”

I’d argue that, by default, we tend to think of our selves as much more whole, impermeable, and unified than they are; the Pyrex or glass Mason jar to Tupperware’s plastic tubs. That’s a tidier and more reassuring perspective, that our selves are less porous, less constrained, and more under our control.

But like the villainous, scheming container of mold with a smidge of pot roast that’s going straight past the sink and into the bin, I think this notion is trash.

Our selves, whatever and wherever they be, are constantly bombarded both voluntarily and through force by incalculable ideas, sensory data, other people, and for lack of a more precise term...vibes.

Having physical selves nigh-perpetually open to our environment and other people—it does not at all follow that “the self” is immune to this, and isn’t also in flux.

To tie back to the earlier discussion of systems, where we set the boundary is telling. To restate the previous in a new context: “where do you and me start? Where does the self end?”

My answer, at least the most unsettling one I’ve for-now settled on is: unfortunately, we’re not the pristine, almost impossible-to-stain Pyrex. We’ve not free to decide exactly and anything we want to be. Even imagining a self in such a way is tinged by one’s existing self.

But, on the translucent plus side, being plastic sullied with myriad variations of delectable and intriguing “chili stains,” our selves are much more durable than the fragile glassware we’d like to think we are.