I’m sitting at my kitchen table eating avocado on toast with chilli flakes and lemon juice on top.

I gesture towards my partner, Kristin, who is standing a few metres from where I’m sat and I say, “Please can you pass me my blue cup, you know the one with the pattern on?”

My blue cup with a pattern on is my favourite cup of all time. It’s massive. It holds probably twice the amount of liquid that your average cup holds. If you’re a client of mine, you’ll probably know this cup because I generally drink herbal tea from it most coaching sessions.

Anyway, so, I ask Kristin to pass me the blue cup with a pattern on.

She nods her head and reaches for it and then says, “You do know this cup is not blue, right? It’s black.”

“No!” I scoff, “It’s blue. For sure!”

Kristin walks towards me with my blue cup with a pattern on and holds it right in front of my face. “See, it’s black!” she says.

I inspect it closely. I get up from the table and hold it under a light.

She’s right.

The cup is black with a pattern on.

What?

I was so sure it was blue. So sure. 100% sure. I would-have-put-money-on-it sure.

And yet I was wrong.

Sometimes, the things we think and even know to be true—about people, situations, experiences from the past and anticipations about the future—are not actually true at all.

We just don’t see it. Because we’re so sure, 100% sure, put-money-on-it sure that we’re right. There’s really no reason to think otherwise.

Or is there?