3.5 stars. This is a good jumping-off point for crystal study, I think, and I love that it touches on possible scientific explanations for the reasons we react to crystals in certain ways...but it's SO short! Only a few resources are listed in the back (perhaps because this isn't a well-documented field), and I would just really have liked to have more detail about everything. It IS the best book I've found for explanations of the how-to for crystals grids, if you're already convinced that they are a valid practice. There is a list of several intentions along with suggested crystals and layouts.