*SPOILER ALERT*
Sephiroth's decendance into madness is not that hard to understand. In Nibelheim, he found out that he was born to become a monster. Since he was born, he knew absolutely nothing about his mother except what Hojo told him, which was that his mothers name was Jenova. This, however, was untrue. Lucrecia was his mother. He was only injected with Jenova cells while he was still in Lucrecia's womb so that he could become a super soldier. When he found this out, he Locked himself in the Shinra Mansion's basement and read all about the Jenova Project. This infuriated him, and that's how he was driven to madness. I mean, that's a lot to take in! Look at it from his perspective. He found out he's been lied to his whole life and was born to become a monster. That's enough to drive anyone off the deep end. Well, after he came out of the Shinra Mansion, he massacred the town of Nibelheim and the rest is history.
And now, what I really wanted to say...
Another great game in the Final Fantasy series is Final Fantasy: Tactics. I liked quite a few things about it. Like, I've always been fascinated with the zodiac, and to see them personified into horrific monsters who's a$$ I had to kick was pretty awesome. Another thing was that, this game wasn't one that you could win just by being strong enough. It was one that you had to play with a strategic mind. If you just went in and tried to muscle your way through, you probably didn't get too far before you got stuck. And, honestly, I think that one of this game's themes is to believe in what you believe in and do what's right, no matter who's against you. I mean, Ramza was labeled a heretic by the Church of Glabados and was pretty much made the enemy of the entire land of ivalice, just because he found out the Churches secret. And in the end, he didn't recieve any recognition for saving the world. He was still looked down on, and one of his most loyal friends was burned at the stake for telling his story. He did what was right based on what HE believed. Which is definately one of my personal philosophies on life.
*END SPOILER*