In +1596 Sun I-khuei complained in introducing his discussion of smallpox that 'the specialised practitioners today take [their treatments for] smallpox as secret techniques and forbidden prescriptions'. Each taught only the views of his own tradition, so that diverse views were never reconciled, and no single best method could emerge. Hsü Ta-chhun wrote (+) that there had always been arts of this kind. Some of these restricted techniques could only be handed down by eccentric hermits, Taoist adepts, Buddhist high monks, or even gods. They had to be protected from the vulgar who, unaware of how arduous it was to obtain and master them, would take them lightly and ignore the special precautions, even the reverent frame of mind, that were mandatory if they were to be effective. It begins to look as if the inoculation for smallpox was exactly the kind of thing which would have been transmitted in this way from Sung or before to Ming times.