The mind does not belong to the same element as the body; the body belongs to the physical, the mind to the mental element; the latter cannot be measured or weighed or made intelligible by physical instruments. Those in the world of science who are trying and hoping one day to produce machines which make thoughts and impressions clear, if ever they are successful, will only be so in the sense that the impressions of thoughts affecting the physical body will be felt by their instruments, but not the thoughts from the mental sphere; for the mind alone is the instrument that can take reflections from the mind.