Thanisarro's internet PDF called: 'Shape of Suffering' is the only publication I know of that provides a practical guided meditation through each of the conditions. Buddhadasa's work is good but 'Shape of Suffering' is the most practical. If you follow the meditation guidance in 'Shape of Suffering', you can decide for yourself whether the explanation is true or not. Most of the other interpretations are mere unverifiable meta-physical theories. Regards