Dr. Svoboda's original work on the constitutional types in Ayurveda has been considered a classic for many years. His new revision and expansion of the subject comes after much further research and practical experience. Dr. Vasant Lad points out: "The healing science of Ayurveda is based totally upon the knowledge of "prakriti", the individual constitution. If every individual knows his own constitution, then one can understand, for instance, what is a good diet and style of life for oneself. One man's food is another man's poison. Therefore, to make one's life healthy, happy and balanced, the knowledge of constitution is absolutely necessary." (Dr. Vasant Lad is the author of Ayurveda: The Science of Self-Healing, and co-author of The Yoga of Herbs.)