I've had a lot going on for the past week and a half, so it ended up taking me much longer to get through this book than I had expected it to. Every time I'd finally get to sit down to read, something else would happen, and I wouldn't be able to get back to it for the next day and a half.
Interruptions aside, I devoured this book. I was worried that it'd be a bit dry, being an analytical look at the various madnesses of the past. However, the only chapter that really felt like it dragged on was the one that covered the Crusades, and that one only felt like it went on forever because each and every Crusade was covered in such minute detail. The amount of research that MacKay put into this book is just impressive.
Many of the "delusions" mentioned in this book are still very much prominent today. While obviously we don't think that alchemists can turn lead into gold anymore, a lot of people still believe in things like haunted houses, relics, and end-of-the-world prophecies - we're still popularizing criminal figures, and stock markets are still crashing because of get-rich-quick schemes that end up being too good to be true.
It's pretty impressive how well this book has stood up against the test of time. Many of the issues discussed are things that we still see happening today. Even though it was published back in 1841, and there have obviously been many cases that could be added to this book if someone were to sit and write one like it today, the over-all message of the book still works. There will always be people who fall for the strangest things.