If spiritual science is to do the same for spirit that natural science has done for nature, it must investigate quite differently from the latter. It must find ways and means of penetrating into the sphere of the spiritual, a domain which cannot be perceived with outer physical senses nor apprehended with the intellect which is bound to the brain.

In our will, there lives something which is perpetually observing us inwardly. It is easy to look upon this inner spectator as something intended to be taken pictorially; the spiritual investigator knows it to be a reality, just as sense-perceptible objects are realities.

What the spiritual investigator has to do to acquire the faculty of looking into the spiritual world consists exclusively of processes of spirit and soul; they have nothing to do with changes in the body, nor with visions arising from an abnormal bodily life.

Rudolf Steiner Quotes