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February 9, 2012 5:05 AM   Subscribe

The Laberinto of Andrea Ghisi is a 17th-century magic trick in book form. Pick an image from the 60 arrayed in front of you, and tell the magician only which quadrant it appears in. Repeat the process twice on different pages, and he can tell you what image you chose. You can see the trick performed at around 2:20 in this video, play a simulation, or see the book digitized in its entirety.
posted by Horace Rumpole (13 comments total) 19 users marked this as a favorite
This post came about because I was in the stacks of my library looking for something else, and this happened to be on the shelf next to it. I mention that only to point out that I have the coolest job in the world.
posted by Horace Rumpole at 5:07 AM on February 9, 2012 [8 favorites]

43 = 64, so they could actually have added an image to each pile and made them 4x4 arrays instead of 3x5. Although nowadays using an obviously special number like 64 could be a tipoff to how the trick works.
posted by DU at 5:10 AM on February 9, 2012 [3 favorites]

The video is really cool. I think Penn and Teller mention this library in one of their books? Or maybe it was a post here?

The trick in the video is a little perplexing, since there seem to be way more than 3 pages in that book. Maybe that's part of the "disguise" so people don't know it's a magic book or maybe there's more saints?
posted by DU at 5:16 AM on February 9, 2012

What a fantastic find, thanks Horace!
posted by ouke at 5:21 AM on February 9, 2012

All I can think about now: running to the front of my television in the early 90s and picking a card that floated on the screen as David Copperfield asked me to make a series of choices between various cards presented to me. Then being fucking amazed when he picks my card at the end.
posted by Fizz at 5:31 AM on February 9, 2012 [3 favorites]

I am now imagining a page where you guess which Mefite is commenting based on which quadrant their comment appears in in three separate FPPs....
posted by GenjiandProust at 5:33 AM on February 9, 2012 [1 favorite]

The simulation hides the fact that someone has to guide you through the book. The arrangement of figures acts as a mnemonic to tell the magician which page/tables to take you next. Thats the inherent cleverness of the book - not just that three choices provide 64 unique paths but also arranging those paths inside the book.

Its also clear from the book's structure that the author knew he could use 64 images but chose only to use 60 for some reason, perhaps having to do with the icons chosen. Using 60m breaks the symmetry of the tables and on 4 pages there are indeed empty squares signifying the 4 missing symbols.
posted by vacapinta at 6:10 AM on February 9, 2012 [1 favorite]

I'd assume that, since the advent of computers and programming training in schools, the trick to this magic trick is a lot more obvious nowadays.

OTOH, he used 64-bit pathways way before they were popular. Digital hipster?
posted by IAmBroom at 6:10 AM on February 9, 2012

OTOH, he used 64-bit pathways way before they were popular. Digital hipster?

Yeah, computers don't seem to have developed new ways of thinking so much as make its application practical. Paul Otlet tried to create a database out of 3x5 cards and Belgian children. Rabbinical scholars developed citation/glossing techniques by at least the early Medieval period that show they were jonesing for hyperlinks. Egyptian mathematics prefigures techniques we use in computing today and so on.... These are not new ideas
posted by GenjiandProust at 6:52 AM on February 9, 2012 [2 favorites]

Thanks for that, GenjiandProust!
posted by IAmBroom at 8:54 AM on February 9, 2012

I've been trying the method in the last link with the digitised version in the last link, and it doesn't seem to work according to the same rules. Can anyone figure it out?
posted by fimbulvetr at 11:45 AM on February 9, 2012

Never mind. I figured out the Italian original version. It uses a different code than the English version, but is still pretty simple. First picture, then last picture, then middle picture and then count the letters out from the first box.
posted by fimbulvetr at 1:31 PM on February 9, 2012

These slides are a nice way to read about it without having to wade through several screens full of text. Bonus points for side excursion into Choose Your Own Adventure land, and The Name of the Rose.

(This post is awesome, Rumpole.)
posted by obiwanwasabi at 1:27 AM on February 10, 2012 [1 favorite]

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