Selfish Citizens Demand Tyrannical Government
Being tyrannised by your emotions means becoming an agent for that tyranny. If your fear makes you abandon smoking, then you will demand everyone stops smoking. If your unfettered instincts make you revere children then you will demand that everyone reveres children. And inevitably if there are enough selfish people who share the same whimsical notions, they will form groups that demand these notions be enshrined by law. That is, they will set out to force the whole community to adopt the demands of their own feelings (see Political Correctness), which of course is rule by menace, and is tyranny.
Its Hysterical Nature
Being ruled by fears and fancies mean ignoring, so discarding, the restraints of tradition, which supplied an ordered society informed by knowledge free from the corruption of fears and fancies. And replacing it with a disordered society mislead by superstition, which is science corrupted by fears and fancies.