you talk about conversations you had with lloyd blankfine, the head of the biggest investment bank in the world and most important one, goldman sachs who year after year dismissed the vie ability of crypto currencies and then changed his mind. >> i think bitcoin is like a search engine from the 1990s. i don't think that bitcoin is going to compete with the dollar euro, yen as a competitor of currency, but there's this thing inside bitcoin called the block chain. it's a computer science breakthrough, which i think is going to be applied and be able to create, first of all, a digital currency at some point that is a competitor to the dollar, the yen and the euro but also is going to allow us to do very, very highly trusted transactions between people where normally you would want or need a human. like buying tickets, settling a legal contract, stock sales, things like this that have a lot of friction and cost. i think the costs are going to go to near zero as this block chain technology enables it. >> you conclude the book with a chapter, the most important job you will ever have, which