A beautifully designed, easy-to-navigate reference guide that I regularly pick up when selecting oils. It has quick-reference pages, blend recipes, diffuser ideas, and a helpful emotion and energy section. While it is built specifically around doTERRA oils, with their product names included, this book can be a great reference when using any brand of essential oils. Just remember, if you are not using doTERRA oils that while you can follow the diffuser and inhalation methods described in the book, you must not ingest unsafe, non food grade oils. There are several series of the same book. I have series 5, but newer editions include newer essential oils.