The central idea of the book is that babies are too immature for the outside world until they are about 4 months old. Some do just fine once they realize they've been evicted from hotel mom, but some go totally bonkers. That's colic. Calming a baby who is doing his best impression of a pig safety pinned to a hyena (and isn't hungry, wet, or tired) is all about re-creating sensations the baby had in the womb.
First you swaddle the baby - nice and tight. Evidently when they really get going they can accidentally smack themselves in the face with their arms, which seems kind of funny in the abstract, but I'm sure it would not be at 3am. Then you put them on their side or stomach. These are the murder positions as far as sleep goes, but they are the most effective for calming a crying (and therefore awake) baby. Third you crank up your favorite "Best of the Vacuum Cleaner" or "Sounds of the Honeywell desk fan" CD and jiggle the baby around. Finally, pop a pacifier in the baby's mouth, and - if you do everything right- Dr. Karp claims you will have a calm baby.
I have to admit a certain curiosity about how well this magic cure works. You can actually attend classes or watch a video that show the techniques in action. Talk about marketing to a