Originally posted by Raistlin
The party didn't believe Jenova was Cetra. However, Sephiroth did.
I know, but the possibility was present in Aeris' mind, at least at first. "Sephiroth and I... do we have the same blood?"

Also, one thing you people haven't mentioned: it could be a combination of theories. For example, what if the Sephiroth you chase throughout the majority of disc 1 is actually Jenova, though the Sephiroth you meet in Temple of the Ancients(and briefly in City of the Ancients; those brief unsubstantial Sephiroths) are Sephiroth's "projected image?"

Or maybe I'm just a rambling idiot. But it seems to me that since there's some events which the Jenova theory can't explain, and others that the "projected image" theory can't explain, why not combine the two?
Good point. There's no single conclusive answer to everything, which is probably why this's still being debated after so many years. I've long held that Sephiroth used his mind to interact and communicate with Jenova's body, disguising it in his form so he could be *free* again, and out there working his evil. In that sense, it's a projected image, but still dependent on Jenova's body to give it useful substance. This would explain why Sephiroth turns back into his own image after being disguised as Tifa to deceive Barret or Nanaki at the Whirlwind Maze.