Why is there so much poetry in departures? God knows how many forests, let alone poets, have died trying to explain it. For me, it’s something existential: up to this point, we shared a common frame – an existence. You see what I see, hear what I hear, and that binds us together into a single recognizable experience.

Once we step away, everything changes. The common frame vanishes, and we’re left with our separate realities.

That other world still exists, but we can no longer reach it. When we make that big jump into the swimming pool – breath held mid-air, the crash into the water, and then the sights and sounds we know of the world above are gone, replaced by blue-green shimmers and echoes from far away. We have to hold our breath, this is not our place, and that breath we have carries us back until we re-emerge in the world that lent it to us. The departure is – in a way – that leap into the giant pool, and the breath we carry is our memories of what we are leaving behind.

There was a flight, years ago, one frozen night over western Connecticut, on the way back from Mary’s. Somewhere below me there must have been swimming pools, wrapped up for winter and drained of their otherworldly memories, but I had other concerns at the moment. The overcast had been lowering to the west, and in the punishing turbulence, I’d been leery of dipping my rented 172 closer to the carpet of lights below me. Novice that I was, I already knew that scud running at night was not correlated with longevity. I’d been ducking below the cloud cover, tracing my thumb across the dimly-lit map, not liking Plans A or B. Moonlight illuminated a gaping shaft in the clouds above – a column of clear air nearly a mile across, leading up to… what?

I called Flight Service to assure myself that Duchess County was reporting clear weather, and ventured into the breech. Slowly circling, upwards into what felt like the eye of the hurricane, I climbed towards the twinkle of stars overhead. Four thousand, five thousand, seven… then the sea of clouds fell away and I was out on top. In an entirely different world – or perhaps none at all.

Under me, through that portal to the world below, I could still see the Christmas tree lights of Hartford, or wherever, but I had stepped through the wardrobe into something else. White clouds stretched out endlessly below, rolling gently and shimmering in the frozen moonlight. The air was still and clear, with a firmament so deep and intensely dark that I could scarcely believe there was atmosphere above me.

I checked free air temperature as I turned westward. Twenty below. With the Cessna’s “shinburner” cabin heat, I fared a little better, but was glad of the winter parka and ski gloves through which I felt for the yoke and throttle.

This, I realized, must be what space is like. I was alone in my capsule, kept alive by dint of the assembled technology and a small serving of skill. Outside this thin aluminum wall, there was frozen nothingness. Above and below, no trace that man – or life itself – had ever existed. Or even could. I, borne, aloft in my mechanical metal cocoon, might be carrying with me all that had ever been of Shakespeare, Sartre, Picasso. Or love, joy, jealousy and hate, for that matter. Sex. A smile – and the atom bomb. Everything I knew had been, everything from that common context I’d left behind – it was carried with me in that plane. What if I landed, came back to the surface gasping for air, to find a desolation void of humanity? I found myself, inexplicably, holding my breath.

Evolutionary biologists are fond of pointing out examples of evolutionary divergence. A species of cricket that spread westward along a mountain range in China. The moisture-laden wind from the south made one side a lush rainforest; cresting the ridge, the now-depleted wind scorched the northern side into desert. As generations of crickets spread westward, those to the north of the mountains became small, and dull gray to better survive in the arid land; those to the south grew large and green. In time, both had traversed the range and met in the west, but they were no longer a common species. Their separate contexts had become so different that they could no longer rejoin, or even recognize their kin.

This is both the thrill and danger of diving into that big swimming pool. Our time away changes us, sometimes more than that brief interlude above the clouds changed me. Sometimes we reach the surface with only wrinkled fingertips; sometimes we’re unrecognizably different. And sometimes we don’t reach the surface at all – sometimes we decide to stay.

Evolutionary biology aside, we’ve all read about the “uncounted casualties” of war – those who come back, but come back different, and are unable to rejoin the life they left behind. We have been wandering our lush green rainforest, while they have traversed a desert more brutal than we can imagine – how could we recognize them, or them us?

Anyhow, enough philosophy – I’ll leave that to Ellen, who does it much better than I do. Pragmatically, I am on the road again. Dropped off by Devon at the rail station to catch Caltrain (then BART, then the Air Shuttle – sigh) for a flight to Boston. I’m headed for Dartmouth this evening, to do the recruiting song-and-dance for our engineering team. It also happens to be Dartmouth’s homecoming weekend coming up, so I’m staying for the bonfire and looking forward to the camaraderie of old chubbers for a few songs over a few pints on the green. I’ll take photos if I can, and try to bring a little of what I’ve found back the the ol’ common context at home.

But for the moment, I’ve got a window seat in the exit row, a fully-charged laptop, and an inflight movie that I’ve actually wanted to see (“Devil Wears Prada” – but don’t tell Devon!).