This is an astonishing book, written in first person. It is a memoir of the author's life with the "synaesthesia and savant syndrome", a rare form of Asperger's syndrome.
People with synaethesia see numbers as forms with color and texture, and days as vivid colors, and so Daniel Tammet has the ability to see in his mind numbers and days as colors, each number and day having its own distinct color as an attribute. A day with a color, like a flower with a scent! The blue day of the title of this book refers to Wednesday, which, like the number nine, he sees in his mind as blue. "I know it was a Wednesday," narrates Tammet, "because the date is blue in my mind and Wednesdays are always blue, like the number nine or the sound of loud voices arguing."
Daniel is also a savant, with a remarkable ability to multiply and divide given numbers with astonishing speed. He can recite from memory the number pi, 22 divided by 7, or 3.1428571 to 22,514 decimal places, a feat which will take him a little over five hours! He says numbers are beautiful things, and that pi is as beautiful as Mona Lisa.
Like Christopher John Francis Boone, the fifteen year old hero of Mark Haddon's novel, "The Curious Incident of the Dog in the Night Time", Daniel, too, is very fond of prime numbers. "Prime numbers feel smooth, like pebbles," he says. He can recognize every prime number up to 9,973. He can speak in ten languages, including Icelandic, Lithuanian and Welsh, and he has the ability to learn a new language within a few days. He learnt Icelandic, for example, within a week; a most remarkable feat for any human being. He doesn't understand jokes easily, and the expressions on human faces he finds baffling. And like Christopher, he doesn't like to be touched.
He is perhaps the only person in this world with the "synaesthesia and savant syndrome" who has written a book in his own words, without using a ghost writer. What causes this syndrome is a mystery to neurologists; they have been trying to unravel the mystery, so far without much success. They speculate that a series of seizures Daniel suffered in his childhood might have caused the savant syndrome. But this is just their speculation; no one knows the real cause.
For a man who sees numbers and days as colors, this book is written in a simple, bland, colorless prose. Nevertheless, reading this book is a marvelous and rewarding experience. This book will touch and warm your heart.