Beethoven's Symphony no. 9. The embedded video is just the first one I found on youtube, but I don't guarantee it to be the best performance, because I haven't listened to the whole thing. The version I'm currently most fond of is the CSO with Sir Georg Solti: it's perhaps more bombastic than Beethoven had originally written it - sounding more like a romantic era composition than classical - but somehow I think this is what Beethoven would have wanted. Look it up, but for now:
It sounds...like life.
Edit: It also occurs to me that in terms of the emotions it evokes, I should also mention Yuki Kajiura's Decretum. It's a great piece, though for me the power lies more in the memories it evokes of the series that it's from. I can't help but think of certain things that happened in that series when I hear this.