WARNING: THIS COULD BE REALLY DISTURBING... if you are discomforted by deep thoughts about death, DO NOT READ FURTHER.
Recently I had been experiencing a "death anxiety" created from focusing too much on the inevitability of aging, the idea that everyone dies someday. (brought about in part by my grandmother's passing). This line of thought had been furthered by reading Kafka's Metamorphosis, which describes the death of its protagonist in gruesome detail. I contemplated the horror of losing function and being trapped in a blind oblivion... then I came at once to a point where the thought lost all meaning, seemed acceptable even. I realized that the chemical in me which processed fear must have run itself down... the thought of death was no longer frightening because my instincts had diverged. Makes sense -- fear exists as a chemical after all. I realized that death was, paradoxically, both fearful and not fearful because subjectivity is shaped by objective factors. Remove the associative criterion between meanings and emotions, causal relationships between meanings and emotions can be swapped out.
(don't think about this too hard... I experimented with it myself and it almost drove me insane, led me to try to fix my own emotions by forcing my mind to feel a certain way... I got out of it by observing such manipulation a form of evil to be abjured).
What if a person could use emotional cycles, shared by many people, to their advantage? What if they had a will to shape them at all? I had long been confused by the idea that something static and enduring like emotional significance could change; but now I understand it can go -- with utter absurd strangeness -- on and off. Imagine what a person could do by wearing down a population's sense of emotional significance... an entire nation's emotions could be manipulated.