4. The Threshold In Nature and In Man

We may even put it this way: if the men of olden times feared the Guardian of the Threshold, and needed to be fully prepared before they might pass him, we in our day must desire earnestly to pass the Guardian. We must long to carry knowledge of the spirit into those regions where hitherto we have relied only on external sense-perception in combination with the results of intellectual reasoning and experiment. Knowledge of the spirit must be taken into the laboratory, into the observatory and into the clinic. Wherever research is carried on, knowledge of the spirit must have place.