1. Background

There is a long history of using clay to treat human health, physical balance, and psychophysiological balance. The literature is full of empirical examples of clay uses, supported by traditional methods often perpetuated in the form of legends related to recovery. Numerous cultural or worship practices have supported these uses, with or without solid justification, but always for reasons close to vital concerns. In popular tradition it is the earth (in English), the terre (in French), that has a powerful part in supporting life. It is the task of modern scientists to distinguish among the many uses of clays, those that are truly explainable and those that are less logical or even doubtful. It is the job of scientists to integrate tradition into science.