“In an astonishing and now-famous case study entitled The Mind of a Mnemonist, [the Russian neurologist A.R.] Luria writes of a man named Shereshevskii, whom he designates S. . . .

S.s irrepressible power of synesthesia . . . compelled him to see and even taste words, numbers, and sounds. According to Luria, Presented with a tone pitched at 250 cycles per second and having an amplitute of 64 decibels, S. saw a velvet cord with fibers jutting out on all sides. The cord was tinged with a delicate, pleasant, pink-orange hue. And each word and number elicited a graphic image. In S.s own words: When I hear the word green, a green flowerpot appears; with the word red I see a man in a red shirt coing toward me.”

—Jonathan Cott, from On the Sea of Memory: A Journey from Forgetting to Remembering, 2005.