Two Harvard scientists have produced 70 billion copies of a book in DNA code –and it’s smaller than the size of your thumbnail.

Despite the fact there are 70 billion copies of it in existence, very few people have actually read the book Regenesis: How Synthetic Biology Will Reinvent Nature and Ourselves in DNA, by George Church and Ed Regis. The reason? It is written in the basic building blocks of life: Deoxyribonucleic acid, or DNA.

Church, along with his colleague Sriram Kosuri, both molecular geneticists from the Wyss Institute for Biologically Inspired Engineering at Harvard, used the book to demonstrate a breakthrough in DNA data storage. By copying the 53,000 word book (alongside 11 jpeg images and a computer program) they’ve managed to squeeze a thousand times more data than ever previously encoded into strands of DNA, as reported in the August 17 issue of the journal Science. (To give you some idea of how much information we’re talking about, 70 billion copies is more than three times the total number of copies for the next 200 most popular books in the world combined.)