Gripping the tree trunk, I can see it clearly: dead straight, pale grey, about a foot wide. The guide listens to my description with good humour, but he can't see it, because he's blind. The thing is, so am I.
While my eyes failed to adapt to the total darkness in the exhibition, my brain switched to new inputs in a matter of minutes. It wasn't like seeing. I could see. Sometimes I could see things that weren't even there, but waving my hand straight through an object was only a temporary setback. The inferred positions were almost always right.
Location by sound worked amazingly well: when the guide sat down I was able to hear the difference and locate the bench. Navigation by dead reckoning was similarly effective.
Through a simulated forest, street, shop, bus and bar I was almost entirely comfortable, albeit slow and clumsy. By the end, I even caught myself using my habitual acknowledgment "I see it" when responding to directions.
I never saw the exhibition with the lights on, but I have a set of mental images. They're vivid, detailed, and no doubt almost completely wrong.