First of all let's go back to the Slim Shady EP, this is where Slim Shady got introduced to the world. The Slim Shady concept is used for this and The Slim Shady LP which basically is a brushed up version of this with more songs. (this is not trying me to put the album down in anyway).
Then The Marshall Mathers LP comes, his songs switch to a more personal side while Slim Shady of course has a great part too.
The Eminem Show, the songs swift to a more inspirational and entertaining side. By now you're probably thinking, "I already know this", but I don't want to leave these parts out because you need this to understand the following parts.
Encore, what does this mean? It's an artist giving a last performance, the world wanted a album after TES and he gave it, kinda follow up even. Now in the last song of Encore, Eminem kills himself and his audience as we can hear on 5:18: http://www.youtube.com/watch?v=cmR4sy51tQo&feature=related, also there are photo's of this the album booklet.
Now to the cd cover:

He leaves a suicide note, he says sorry to this fans. Why? I see two things: 1. He kills himself to show he's taking a break from music. 2. He makes an opening for a new concept in which is he's taking us to hell, he killed the fans and himself and brings us to hell.
Now we're at Curtain call, the last album of an era which was from 1997 to 2005. It's a greatest hits compilation but this is where he kills Slim Shady and ends this era. And takes a break solo.
Now Relapse, he's off drugs and really starts getting into rap again, that's where Slim Shady comes back from "death", it's like Eminem said, Slim Shady will always be inside off him, but sometimes Slim Shady lays low. Listen to Dr. West and My Darling, this is you can hear him coming back after the break to rebuild his career. And now they're reunited, he and his inner devil. Now we're in hell with Eminem just like he promised on Encore, in the world of him and Slim Shady, killing people and other kinds of fucked up shit.
So there you have it, the concepts up to now (from my standpoint), I might elobrate on Relapse more but since I've written so much already, I'll leave that for another time.
My guess for the future, but this is no suprise, is that he'll go more on the emotional/personal side again, kinda like the switch from The Slim Shady LP to The Marshall Mathers LP.
I hope you enjoyed my little article










