The Membrane and the Metaphor

A psychiatrist named Ernest Hartmann spent years studying people with unusually vivid dream lives and found something larger underneath: a measurable range of temperament running from thick-boundaried to thin. At the thick end, thought stays separate from feeling, sleep is a closed door, the past is filed and finished. At the thin end, sensation and idea arrive together, the border between waking and dreaming goes soft, and the past visits the present uninvited. Hartmann called the trait boundary thinness. He was not, it turns out, the first to notice it — he was only the first to measure it.

John Keats got there first, writing to his brothers at twenty-two, trying to name what made Shakespeare Shakespeare. He landed on a phrase: negative capability, the ability to sit inside uncertainty without grasping after a tidy resolution. That is a thick-boundaried mind's discomfort and a thin-boundaried mind's native climate. Keats went further elsewhere, saying the poet “has no self” — that he can pour himself into a sparrow outside the window and peck about in the gravel alongside it. Two centuries before the questionnaire existed, Keats was describing, in a letter to his own family, exactly what it feels like to have very little wall between the self and the rest of the world.

Samuel Taylor Coleridge coined a stranger word for the same phenomenon: esemplastic, meaning shaped into one — his term for the imagination's power to dissolve separate things into a single new thing. That is not so different from what happens when a memory and a present moment blend without asking permission, or when a feeling arrives already wearing the shape of a physical object. The Romantics called this imagination. Hartmann, without citing a line of Coleridge as far as we can tell, ended up measuring the same trait with a clipboard.

And then there is Wordsworth, who wrote that we come into the world “trailing clouds of glory,” and asked, achingly, “Whither is fled the visionary gleam?” Readers have taken that for two centuries as a poem about the ordinary sadness of growing up. It reads differently once you know that boundary thinness, on average, does thicken with age — that most people's walls harden as they mature, while a smaller number keep something of that early permeability their whole lives. Wordsworth may not have been merely wistful. He may have been reporting a fact: most people lose the gleam, and a few simply don't.

We raise all this because our own James F. Mulhern has written directly into this territory, in an essay called “Thin Places,” which takes its title from the old Irish phrase for ground where the wall between this world and the next has worn thin. The essay traces its own private history of the trait — a mentor who named it in him decades before Hartmann's research existed, and gave him, in a single sentence, permission to stop apologizing for a mind that let too much in. We recommend it to any reader who has ever been told, by a teacher or a parent or their own embarrassment, that they feel things too much or notice too much or ask too many questions. The essay's case, and ours, is that this is not a flaw to outgrow. It may be closer to the raw material of the work itself.

You cannot write a character from the inside, or build a metaphor that actually surprises a reader, unless something in you is willing to let the borders go soft for a while. The membrane is not a defect. It is an instrument — strung a little more finely than most, built to pick up what a thicker wall would never let through.

— The Editors