The bizarre fact that psychical research has made little progress since its inception lays the ground for an engaging discussion on the limits of the knowable.
These visions are both 'real' and 'unreal' (in a strictly materialistic sense). They emanate from the 'world soul' and the individual counterpart, the intuitive ego. They are an integral part of our existence which manifest themselves in different guises, based upon the prevailing culture of the percipients.