Nero

Roman emperor (54–68 CE) who began well under Seneca and Burrus's guidance and ended as a tyrant who murdered his mother and wife, persecuted Christians, and ordered Seneca to commit suicide — making him the historical test case for whether philosophy can restrain political power.

Represents the failure of the philosopher-advisor model — Seneca's attempt to guide Nero toward virtue failed, and Nero's increasingly erratic cruelty suggests the limits of philosophical influence on power — the case against Plato's philosopher-king when it meets actual political psychology.