' Now, those people who, through very 
advanced and special exercises, are 
able to detatch their Astral bodies from 
their physical bodies, will be able to 
see a light, silvery-blue thread, such 
as you saw yourself, linking their 
physical and Astral bodies.  Their 
Astral bodies, likewise, are visible 
during the time that the separation 
lasts.  It is these same electrons which 
form your Astral body and which 
create the visible effect of the thread.'