By Maria Popova (themarginalian.org)

The history of our species is the history of mistaking the limits of our imagination for the limits of the possible. It is salutary, I think, for us to be reminded regularly that this world is far wilder and more alien than we suppose it to be, that flowers are not what we supposed them to be, that eyes are not what we supposed them to be, that life and death are not what we supposed them to be, that a self is not what we supposed it to be.

We come to know a world the way we come to know a person — by learning its depths and its limits. It has always tugged at the human imagination to touch these extremes — to reach its poles, to conquer its peaks, to balance life on its sharpest edges. But it is the depths that have enticed and eluded us the longest.

Previously unknown giant dragonfish (Bathysphaera intacta) circling the Bathysphere by artist Else Bostelmann, 1934

At the end of the nineteenth century, upending the long-held dogma that no life existed below 300 fathoms, a series of landmark oceanographic expeditions plunged deeper and discovered the magnificent creatures of the deep, discovered how magnificently deeper the deep really was than imagined. And then, in 1875, the Challenger expedition let a weighted piece of rope drop and drop and drop into the South Pacific, until it sounded a depth of 4,475 fathoms — 8,184 meters. They didn’t realize the spot was part of an immense trench — an upside-down mountain range at the bottom of the world. Over the next century, more expeditions and better technologies continued and refined the measurements, until the bottom of the Mariana Trench was sounded at around 10,984 meters — half the Andes stacked atop Everest.

To touch such depths with the mind was already staggering beyond measure. To touch them with our animal sensorium seemed unimaginable. As a human foot fell on the dusty surface of another planetary body, the deep ocean remained more mysterious than the Moon. “Who has known the ocean? Neither you nor I, with our earth-bound senses,” Rachel Carson wrote in her pioneering essay Undersea. And yet when William Beebe plunged his Bathysphere into the deep, the unimaginable became possible — this, too, is the history of our species.

William Beebe inside the Bathysphere (Wildlife Conservation Society Photo Collection)

Nearly a century after Beebe, Scottish geoscientist Heather Stewart set a diving record with her 10-hour descent to the bottom of the Mariana Trench with the Bakunawa submersible, one of the most impressive and costly technologies humankind has created. On a fascinating episode of BBC’s In Our Time — my favorite radio program — she recounts, in words not dissimilar to astronaut Sally Ride’s exuberant description of what it’s like to launch into space, her experience:

There is the moment you’re sitting on the sea surface and get the clear-to-dive call, and that color change as you start to fall through the water column… the change from clear water on the sea surface through the brightest shades of blue down to absolute pitch-blackness… And all of that, you’re sitting in silence, and that is so humbling as well as so very exciting, because after a few hours you start to come to the sea floor… That moment you turn on the lights of the submersible and start to see the sea floor coming up underneath you is absolutely fantastic.

All the while, she reflects, her brain is scrambling to parse this surreality and integrate it with her existing understanding of the world by putting it in a geological context, trying to form a working hypothesis of what kind of world might be the bottom of the world. But we are captives of our frames of reference and we habitually forget that the imagination of nature will always be greater than ours, because it imagined us: Suddenly, out of that blackest darkness — as in life — spring the most surprising colors:

The colors that you can see on the sea floor can take your breath away… yellows and blues and all of these chemosynthetic bacteria that are living off the mineral content coming out of these vents, the cracks and fissures on the sea floor.

Endpapers of the classic 1959 children’s book Little Blue, Little Yellow by Leo Lionni.

But one doesn’t need a $30-million submersible to taste the sublime strangeness of the deep. We have invented another technology to take us to those places hardest to reach. In this fragment of her sweeping five-part poem “The Depths” (translated by my mother), Natalia Molchanova, considered the greatest free-diver of all time, invites our earth-bound senses into the most alien depths of this world:

And I perceived
        nonexistence.

The speechlessness of eternal darkness
                and its boundlessness.

And I emerged from time,
                it
                        poured into me,
And we grew
        still.

I lost my body between the waves.
And I reached emptiness,
        peace,
touching the secret of the ocean —
a bottomless blue abyss

I turn inward,
        and remember
Self.
    I — light.
        And I gaze intently:
In the depths breath
        is born.
I merge with it.
        And I emerge into the world…

At the age of 53, Molchanova plunged into the sea off the coast of Spain and never emerged, touching, somewhere at the bottom of the world, the hardest thing for a human being to touch — peace, total and austere as pure spacetime.