Written by an eminent economic historian, this book outlines what I believe is the standard view of bubbles, crashes and financial panics -- three closely related but not identical topics. The author's account goes something like this:
From time to time the price of some class of assets starts to rise and people get excited. Often there is some good reason for this -- railroads, canals, tech companies and so forth are real productive assets and people realize at some point that they have been previously underestimating just how productive. Tulip bulbs with exciting pretty patterns also qualify -- a bulb that produces a new kind of flower is a capital asset, since you can produce many such flowers by cutting. The first third of the book documents this process.
As speculators pile in, the price of the asset grows higher than can be justified based on future cash flows. In addition to sincere promoters of the new asset, there are incompetents and frauds promising returns they can't reliably deliver, or have no intention to deliver. Insiders notice this and cash out. At some point the cycle goes into reverse -- often due to some prominent failure, sometimes due to simply a lack of new investors. Prices falter and fall. When people notice the decline, there's a feedback loop where everybody wants to sell "before the crowd" -- hence, the crash. The author traces this pattern with examples going back to the tulips, with special emphasis on English, French, and American panics from the South Sea bubble through 1929. Reading the book at the time I did, it was impossible not to think of Bitcoin. The second third of the book describes the crash and shows that it feels remarkably similar whether it's stock in the South Sea Company or a 2000-era Dotcom company.
Sometimes, a bubble can burst without drastic effect (e.g., the Dot-com bubble.) But sometimes the bubble is big enough, or has sensitive-enough investors, that it causes larger scale disruption. In particular, if people or banks had been borrowing against the now-worthless asset, the individual or bank will now be under water. At this point, creditors notice that they need to get their money out before the insolvent party goes bankrupt -- and there's a rush to call in loans and de-leverage. This cycle, if it grows big enough, is a panic. Anybody who was paying attention in the fall of 2008 knows what this looks like.
The last third of the book is devoted to discussing responses to panics. The author looks particularly at doing nothing, at declaring bank holidays, central bank cash infusions, and international rescues. The author notes that "bank holidays" [and their shorter-timescale equivalent, the trading circuit-breakers] rarely work -- those devices leave investors more anxious to get out quickly, while they still can, the next time. "Do nothing" is questionable: some problems do go away on their own as investors take their losses and move on; other times, the scale of financial deleveraging does a great deal of unnecessary damage. Rescues (domestic or foreign) do work, but have corresponding challenges -- they risk moral hazard,, and sometimes the rescuer doesn't have enough money to go through with it. The author at length concludes that we are little advanced over Walter Bagehot, the mid-19th-century economic journalist -- it's good to do rescues, when we can, but without being too consistent or predictable about it.
The book is written for both a professional-economist and lay readership. The author is at pains to draw contrasts between his view and either Marxists who assert that all investment and money is a sham or radical neoclassical types who assert that there are no bubbles, investors are always rational and things that look like bubbles and crashes are a misreading of the evidence. I found the book generally easy reading though was confused about technicalities at some points.