The need to possess readily available tools of inducing such mind-healing or mind-building functions also originated a variety of semi-medical experiments such as palming. Palming is based on the unique concept assigning extraordinary powers to the "Memory of Black." This is achieved by shutting the eyes and covering them with the palms of the hands (the fingers being crossed upon the forehead) in such a way as to avoid pressure on the eyeballs. Remembering Black brings universal relaxation, improves the sight, and also relieves tension and pain. "Why the memory of Black should have this effect cannot be fully explained, just as the action of many drugs cannot be explained; but it is evident that the body must be less susceptible to disturbances of all kinds when the mind is under control, and only when the mind is under control can Black be remembered perfectly," claims W.H. Bates, M.D., one of the pioneers of ophthalmology.