BBC Sounds, Music, Radio, Podcasts.

So far, these talks have been riffing off the ideas that inspired the series.

We've heard about AI governments, human extinction, digital graveyards and circadian rhythms.

But this last riff is more kind of appreciation, a love letter to the forest.

Maybe that sounds sort of abstract, but like our other talks, it's all based on fact,

on the things that trees give us humans, culturally as well as biologically.

It's written by David Haskell, a biologist and author whose books include The Songs of Trees and the Forest Unseen.

Here's David Haskell's Love Letter to the Forest.

Ah, forest.

No scribed or spoken word is sufficient for your sylvan beauty, for the amazing filigrees of your inner life.

You draw me beyond the language of words.

And so I reach out to you.

I lift a small handful of forest soil and bend my head to inhale.

There are a dozen textures here.

Fine root filaments, mineral grit, spongy humus,

a tickle of tree bud scales, tumbling flakes of leaf. Here, in my nose, is your generous, rounded earth aroma, your sharp wit of tannins, and the spicy exuberance of microbial life. We breathe each other.

Every inhale brings life's catalyst, oxygen.

Half of this precious gas was made deep inside your emerald leaves.

The other half of the oxygen in my breath comes from your comrades, the ocean algae.

Forest and ocean slake the oxygen thirst of every cell in my body.

My exhale sends carbon dioxide to the air.

You'll capture some, welding my breath into wood, fruit and root.

...