It’s human nature to yearn to make a lasting impression on the world. We toil away in cubicles to prove our worth to a corporation, search emphatically for a soul mate, strive to leave a legacy or indelible mark on a generation or a society. We do these things to prove to ourselves — to others — that who we are and what we do is singularly unique, to rest in the comfort of knowing that our existence has shifted the universe, no matter how insignificantly. But when we do move on, we’re inevitably replaced. We aren’t the indispensable aspects of our jobs or our relationships; we’re merely a placeholder the system needs to survive. So why do we strive to make ourselves so essential? What does it really mean to be irreplaceable?