It’s tiny, the size of half an s, in the middle of my screen. It creeps along the line of print, negotiating ‘trucks and drivers’ with slow aplomb.

Little does the spider know that the creatrice of worlds is about to press the red cross in the corner of the screen. It’s flipped into a new reality: teetering on the rim of my daughter’s funky glasses, staring into the green of her eye. Should I change the screen-saver to a field of grass, or a web? Or tell the spider nothing’s really changed; the merest membrane’s been removed. It’s all in the way it seems.

Why shouldn’t this happen to us?

One day we’re complacently decoding the same old same old, then zip, that background’s whipped away, and everything looks strange — we’re flipped into one of our other realitites: an imagining, a work of ‘fiction’, the dream behind the substance.

(In which case, don’t panic: keep your feet on the screen and make for the titanium rim at the edge of the world.)