I experienced this practice and found it sharpens the mind and clears the senses. The incense cones burn at a very high temperature and the searing pain is immense - but also highly localised. Beneath the skin of the scalp is the hard bone of the skull so damage is mostly skin-related, although the pain can continue for some time. Within Chinese medicine, however, moxibustion is very well-known as a method for clearing qi-energy channels and preventing or reducing the chance of infection. These cones are placed along the Governing Vessel and the qi, jing (and developing shen) circulate up the back and over the top of the head before descending down through the centre of the face and into the upper mouth. The tongue connects the upper mouth with the lower mouth so that these congealed energies can freely pass down into the Conception Vessel and into the groinal area (this is the circulation of the microcosmic orbit). I suspect Shi Zhide started this practice in 1288 CE as a means to 'unblock' excessive 'yin' energy (or 'negative' qi) trapped in the head area so that the habitual ignorance of humanity could be more easily 'broken' when the Ch'an meditative method is applied. As I was ordained in a 'fighting' order of Cao Dong monks - this practice was also believed to open the energy channels to such an extent that no incoming power from another's martial blow could cause any damage! As the incoming energy connects with the opened energy channels - it is simply 'absorbed' (like water rushing down the drain) and immediately redistributed throughout the system with no blockages being caused. Whatever the case, the mind must be 'stilled' and 'expanded' and this medical ritual assists this process.
Peace in the Dharma
ICBI UK - Admin