Early on in human space exploration it was realised that jumpgates caused a strange sensation. The effect causes and instant drug like high followed by addictive qualities. The repeated effects can also induce psychic powers in those experienced users.
There are generally three kinds of Sathraist. The spontanous kind who by chance or intention are converted by travel without dampers. The second group are communities of Sathrasists that split from the mainstream of humanity to live among themselves outside of judgement by the Church and state. The live on distant planets unconnected to the Known Worlds. The last kind are hidden Sathraists that work towards a Sathraist agenda within society.
Rumours of the Imperial Eye being run by hidden Sathraists persist and date back to its infiltration in earlier incarnations.