I liked this book as it is only focus is about interest.
It starts with a good historical research. It was interesting to learn that interest was created before money itself! And the definition of interest is in the title of the book. When you borrow money, you need to pay a fee for the time you use to compensate the other person for the time it doesnt have it (and risk of not getting back)
Then goes with the evolution of money and interest. Interest has been critical for trading and economical expansion. Interest has always had a bad name due to usury, that is the abuse of people via huge interest rates. We still have today with credit cards and next-payday companies.
The author says that interest is necessary if not, there is a economical stagnation. But, then comes the interesting thing. The usage of interest in the financial engineering. The low interest rates looks like they are source of most of the financial crises we have seen. The idea is, if your savings don’t produce a decent interest (at least above inflation), you lose money. So that has pushed companies to borrow cheap money and invest anywhere the interest is higher or get to risky activities (mortgage subprimes?). That produces not real economical growth, as companies don’t borrow money for create or improve products (R&D, expansions, etc) but for creating value to shareholders (increase the share price), that is an excuse to get rich quickly. Somehow it is difficult to believe how important is debt nowadays.
As well, something very interesting is the construction bubble created in China due to the low interests rates. I have never read about it.
Most of central banks have played badly with the money printing machine and trying to keep interest rates low with the excuse to help people but at the end of the day, only companies had access to that low rates.
Like everything, you need a balance. You dont want usury but if you manage to save some money, you want some return from that if you keep it in a bank, and that as well, keep companies in check so they need to be sure about the risk they take when taking investment credits.