If you were a medieval scholar reading a book, you knew that there was a reasonable likelihood you'd never see that particular text again, and so a high premium was placed on remembering what you read. You couldn't just pull a book off the shelf to consult it for a quote or an idea.
Joshua FoerTo attain the rank of grand master of memory, you must be able to perform three seemingly superhuman feats. You have to memorize 1,000 digits in under an hour, the precise order of 10 shuffled decks of playing cards in the same amount of time, and one shuffled deck in less than two minutes. There are 36 grand masters of memory in the world.
Joshua FoerOne trick, known as the journey method or 'memory palace,' is to conjure up a familiar space in the mind's eye, and then populate it with images of whatever it is you want to remember.
Joshua Foer