The first edition of this book came out in England in 1990 under the title The Fragrant Pharmacy. You only have to look at the contents and index to see it covers just about every aspect of aromatherapy, health and home. As a full-time professional aromatherapist it is my primary source of information, indeed, it is known "in the business" generally as "the bible of aromatherapy". I doubt there is an aromatherapist in the world who doesn't use this as their reference book, because it is profoundly practical - giving answers to questions you didn't think had any answers. Looking at the many books written after this, its clear where their ideas came from.
If you want practical advice, with detailed recipies and instructions, whether just for home use or professionally, this is the book you need. Every recipie that I have used from this book proved safe, and works, and I wouldn't say that about any other book on the market. I also know for a fact of several vets who routinely use the information in the animal chapter to beneficial effect. Check out her other titles, and you'll see this woman writes in depth - Fragrant Mind, Fragrant Heavens, Aromatherapy for the Healthy Child, Aromatherapy for the Beauty Therapist,and Aromantics (also known as Scents and Scentsuality). Worwood has done research on aromatherapy, and was once Chair of the Research Committee of the International Federation of Aromatherapists. She knows what she is talking about, having been a working clinical aromatherapist for years. In the aromatherapy world she has the highest respect because without her, well, what would there be ...?