People toss around the term "mind-blowing" a lot these days, but when it comes to knowledge that is capable of rupturing your mind, this video from CGP Grey pretty much takes the proverbial cake.
Because, as you're about to find out when you watch the episode above, you are not 'you'... you are actually two brains residing in one person. And one of your brains is just a silent (potentially unwilling) passenger, along for the ride.
Creeped out yet? It's only just getting started.
We've all heard about the left brain/right brain divide, and most of us have been told that it doesn't really exist. And that's partly true - the old-fashioned notion that certain behaviours and traits are controlled solely by one side of the brain doesn't really pan out. But what is real is the fact that there definitely are two distinct brain hemispheres - a left and a right.
These hemispheres each receive half our visual information, and direct half our movement - the left brain controls the right side of our body, the right brain controls the left.
And these two hemispheres communicate through a 'wire', or series of nerves. But, as CGP Grey explains, that wire can be severed, and back in the day, this procedure was performed as a treatment for epilepsy.
This wire-cutting can leave people with what's known as 'split brain', and research on these individuals is, quite frankly, unnerving.
In fact, as CGP Grey breaks it down, it becomes clear pretty quickly that, in people with split brain, the right hemisphere can perform actions that the left hemisphere has no idea about, and has to try to make up a story to explain it.
We don't want to spoil too much, because it's really, really worth watching the video to understand the full extent of what's going on. But we'll paraphrase CGP Grey and just let you know that right now, there are two of you watching this video - one getting its mind blown, and one mentally rolling its eyes at the obviousness of it all.
And if that's the case, then which one is really you? (Oh god, we went there. Next-level creepiness.)
But that's not all. In a follow-up, CGP Grey partnered with some of our favourite film makers over at Kurzgesagt - In a Nutshell to demonstrate that we're not even just two: we're so, so much more than that.
The pile of meat that makes up our bodies is actually trillions of tiny individuals that each has a life of its own. So at what point do they start working together as one, and at what point do they actually become you?
What else can we say but: