The book is thin and short, but practical and very well explained. You don't feel bored of reading it. One must try and see how it works or it doesn't work. I only tried Hildegard von Bingen's Amethyst water and it seems working by internally taking it and externally on my face (is it a Placebo Effect?) All of Michael Gienger's crystal books have beautiful photos that please my eyes! Only thing what I don't realy care about is "A Quartz Glass Test Tube". I would simply use a tranparent white glass for crystals that are not suitable for direct contact with water. I agree 100% to use rubbing alcohol in water for sterilizing!!! One never know how dirty crystals are. They grew in caves, dark areas and under the earth where lots of germs grow. It's better if we worry more about bacteria than negative energy of other people. We are talking about healing by drinking it. Even just to place a crystal on the body, I'd wash and disinfect it in order to avoid skin disease. Let's be a little more realistic about the subject with spiritualism.