I just read Born On A Blue Day [amazon], by Daniel Tammet. It’s subtitled ‘inside the extraordinary mind of an autistic savant’. He really is pretty extraordinary – a high functioning autistic savant syndrome synaesthete of the first order. First paragraph:
I was born on January 31, 1979—a Wednesday. I know it was a Wednesday, because the date is blue in my mind and Wednesdays are always blue, like the number 9 or the sound of loud voices arguing. I like my birth date, because of the way I’m able to visualize most of the numbers in it as smooth and round shapes, similar to pebbles on a beach. That’s because they are prime numbers: 31, 19, 197, 79, and 1979 are all divisible only by themselves and 1. I can recognize every prime number up to 9,973 by their “pebble-like” quality. It’s just the way my brain works.
Tammet is famous for having recited pi to 22,514 digits, from memory, on International Pi day, in 2004, and then he learned to speak Icelandic in only a week. Maybe you saw him on the David Letterman show (I didn’t); or on the BBC documentary Brainman. (YouTube has some bits, including Letterman.) He’s also got a blog.
Anyway, I’m real sorry Wittgenstein never got to read this book. All that stuff about ‘secondary sense’, in Part II of PI - not to mention the fact that Born On A Blue Day reads in this very winning, Wittgensteinian-simple sort of way; strangely affectless, odd-angle parables; the quality of the prose. He describes how he sees pi as a landscape of color and it comes off half way between Data, on Star Trek, and a sort of Tolstoyan-pious, ‘How Much Land Does A Man Need?’ thing. Then, in the final pages, he converts to Christianity, much as Wittgenstein would have wanted him to. (He converts to Christianity after reading Chesterton.)
I still remember vividly the experience I had as a teenager lying on the floor of my room staring up at the ceiling. I was trying to picture the universe in my head, to have a concrete understanding of what “everything” was. In my mind I traveled to the edges of existence and looked over them, wondering what I would find. In that instant I felt really unwell and I could feel my heart beating hard inside me, because for the first time I had realized that thought and logic had limits and could only take a person so far. This realization frightened me and it took a long time to come to terms with it.