4. Corruption of Power
The Doctor is arguably one of the most powerful beings in the universe. He is basically immortal, has fought and taken a terrible toll against countless races - including his own - escaped from seemingly impossible situations time and time again, and has now managed to remove himself from every database in the universe. Why did he do this? Because he began to believe his own legend. He was in danger of becoming drunk with power, had used and even abused it so many times, that he was no longer seen as a healer but a warrior. He didnt just rectify injustice he sometimes caused it. He used fear as a weapon, and this didnt separate him very much from those he fought against. Abuse of power is a common problem at all levels of our society and apparently throughout the universe. How many times have the oppressed turned around to become the oppressor? It is good to feel empowered, but not to the point that you use that power to hurt other beings. This is why the Doctor needs to never travel alone and consequently why human beings need to always remain open to the viewpoints of other people. We have to keep reminding each other that were all in this together, were all worthwhile, and differences are to be understood and celebrated. Children experience power struggles from a very young age. They have to learn how to deal with the bullies on the playground while not becoming one themselves.