Charles S. Wolfe, Amazing Stories (1926)
“ His voice sank to a whisper. "It is this fact that makes my great invention possible. The friction set up produces faint currents of electricity. It is Nature's own generator. The currents are faint, weak, but they are there. And they vary in intensity in proportion as the rushing blood stream surges and ebbs. Thus they have imprinted on them all the characteristics of the thought that gives rise to them. They vary in the individual. Some minds can generate a current one hundred—yes, one thousand—times greater than others, but all minds generate to some extent. ”
