What makes things last, and what do very different lasting things have in common?

From the brain's point of view, what is the secret behind how music works, and why might a space alien not be able to understand the concept of music?

Why does glass in medieval cathedrals look thicker at the bottom?

And what does this tell us about the world's religions?

What was the most important weapon in ancient history and how did it completely disappear?

Today we're going to talk about the concept of persistence

from sharks to Roman concrete to DNA.

So get ready for a great brain stretch.

Welcome to Inner Cosmos with me, David Eagleman.

I'm a neuroscientist and author at Stanford.

And in these episodes, we dive deeply into our three-pound universe

to understand some of the most surprising aspects of our world.

Today we're talking about how things persist.

This is an I-Heart podcast, guaranteed human.

I want to start today's episode by talking about Greek fire, which I'm obsessed with.

This story begins with a refugee named Kalinikos who arrived in Constantinople in the late

600s, and he handed the emperors a weapon that he'd invented and this completely changed warfare in the Mediterranean.

His weapon was known as Greek fire. Think of it like a flamethrower a thousand years before the

invention of the modern flame thrower. Greek fire was a thick liquid. It was petroleum-based

and you'd hurl this in pots or you'd blast it from siphons, and it would burn on the water.

And the key is you could incinerate the enemy's ships this way, and no one had ever seen anything like this.

So the Byzantine army immediately leveraged this as a defense that broke the Arab

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