The origin myths of the Aztecs believes that the gods themselves sacrifice themselves.

They let out their own blood to create life on earth.

Hello, I'm Neil McGregor, and in this series of podcasts,

I'm looking at objects to see how shared beliefs have helped shape societies.

Now we're focusing on the theatre of faith, exploring the public ceremonies where whole

communities come together to sacrifice and to celebrate. This episode is about shedding blood for the gods.

This is the BBC. So here we have an eagle warrior holding a blade, and this knife would have been used for the cutting out of a human heart.

The association...

Can we just stop there from? That's quite a statement.

Sacrifice. The Latin origins of the word mean nothing more than doing a sacred or a holy thing,

but it says a great deal about the religious traditions of the ancient world

and how they've shaped our habits of thought, that this holy thing goes far beyond the idea of a mere offering or a gift.

Sacrifice implies not just putting something highly prized forever beyond our reach,

but effectively destroying it, in the belief that a greater purpose can thus be served,

communion of some kind with a higher power.

The pouring of wine into the earth as a libation

or the burning of costly incense are obvious examples.

These can never again be used.

But sacrifice can and frequently does involve the spilling of blood and the taking of life.

And that was very much the purpose of that knife in the Mexico room at the British Museum.

It's a hugely symbolic object.

This would have been held by a priest, as a sacrificial victim,

...