Charles T. Tart, PhD, is emeritus professor of psychology at the University of California, Davis, as well as the Institute of Transpersonal Psychology. Here he reflects upon his classic article, published in Science in 1972, on "states of consciousness and state-specific science". His ambition, not yet realized, is to inaugurate a new approach to science in which researchers would enter into altered states of consciousness. He examines the obstacles to realization of this novel objective - particularly the human tendency to cling to ideologies. The discussion includes meditation, hypnosis, dreams, and the use of psychedelic drugs.