Mikki's Translation Section VIII
The way that man becomes aware of influences outside his physical world depend on two things - one internal to the person, and one external.
Man is too stupid to be able to figure things out if the operating principles were too terribly alien to what he is used to. However, there are definitely some things that are still too deep for mere mortals to figure out. Luckily, some spirits have been able to overcome Man's ignorance, and show up anyway.
We're going to ignore the petty wars between factions of spiritists and examine how people communicate with spirits.