(Theory) Symbolism of the Mangekyō Sharingan
This won't be an expansive theory as my theories usually are (if you know me of course). However this is an interesting one, I assure. Alright it's about the Mangekyō Sharingan.
The following ninja possessed the Mangekyō Sharingan...
All of the people stated above used the Mangekyō Sharingan for power. Regardless if they're seen as a hero to you (Itachi, Kakshi..) or a villain (Madara, Sasuke, Obito..) or something else.
Now we also know something else that ties the Mangekyō Sharingan's together (unless you're Obito).. Blindess. If you use the eyes too much your eye sight deteriorates and you risk going blind. Now what does this represent..?
Well what does power coincide with... greed. Now tie them together and what do you get..?
Greed and Power blind you. Now what would that make the Eien no Mangekyō Sharingan then? Simple, the greatest sacrficies and acts of evil will give you a different view of the world. The act being disrespecting the dead and stealing your brothers eyes.
What do you think? Thanks for reading