What was the best way to have an honest conversation with another person? Naturally, it would be a conversation in the dark. In such a situation, where one couldn't see the other person's face or expression, they would inevitably relax and lower their guard.
This was just common human psychology, not that Klaus was an expert or anything close to a psychological thinker. It had already been proven correct by many wandering and curious researchers.
A great example of this was confessional booths, where people found it easier to reveal their sins when shielded and protected by a barrier of anonymity. Another would be late-night conversations during gatherings or perhaps camping trips in the night, where darkness seemed to dissolve inhibitions, allowing people to speak more freely without the weight of judgment in another's gaze.
Truthfully, nobody needed to be a psychological expert to know that people found solace in the unseen and comfort in the absence of watchful eyes.
