First, let us explain that there are 129,864,880 unique books in the world — most printed long before the Internet, no longer published, and sitting on shelves with their acidic paper slowly deteriorating, sending words into oblivion. Google, in a wonderful-yet-controversial side project, has been trying to save this knowledge by scanning books with an Elphel 323 camera and serving them free of charge to the public. To date, Google has digitized 15 million books.
Now, Google has launched an Ngram Viewer to help you search old books for topics — kind of a “trending” analysis for any given period of time before the Internet and its ADHD cousin Twitter. Above is a peek at the number of published instances of sex vs. chocolate since 1800. Chocolate, it seems, is a relatively stable interest, while sex crept up in the 1920s and spiked after 1960. Was it the advent of world wars, modern communications, or perhaps birth control? Ponder away and try Google’s book searches here, or read the entire texts for free at Google Books.