With debt came the notion of the value of time, and with this came the concept of the price of money: the rate of interest.

Money buys freedom: the essential promise which makes it so attractive is that, armed with money, you can change your world by gaining more control over your life.

In contrast, the bottom-up economy is organic. It’s an evolutionary system of trial and error, where the market, based on prices, preferences and scarcity, organises the economy and society. Prices and profits, rather than plans and priests, determine whether something is working. People involve themselves in the bottom-up economy willingly, rather

The rate of interest isn’t merely a price; it is also a code, a mini-encyclopaedia of information about the person we are lending to, the chances of success, the risk in the region, the competition in the market, the technological infrastructure, and a whole host of other variables.

Money is a force that dictates the flow of people, goods and ideas around the globe. Our efforts and talents are assessed by it; so too is the future.

Each of us has heard the mantra that money is the root of all evil, yet money is also an instrument of peace. Rather than kill their neighbours for food and property, the newly sedentary farming societies learned to trade using money.

If society is based on a rigid caste system, it’s easy to rule. Terror is a dominant tool of control and institutions and religions tend to be based around fear and strictures. In a society mediated by money, where social status is somewhat mobile, rationality gains prominence over emotion and hard thinking challenges rule following.9

It turns out brain size does correlate with group size: the neocortex, the part of our brain that deals with complex thinking and reasoning, grows in primates relative to the number of fellow primates they are likely to live with. Brains evolve to handle the number of social contacts we are going to have.

For 400,000 years, the technology that most influenced human development was fire; the contention of this book is that the crucial technology shaping humanity in the last 5,000 years has been money.