@Omicron - I will not comment on much because of spoilers, but there's something I wanted to point out because it often tends to get lost in the shuffle and I don't want it to be.
A few scenes beforehand, we're told by Sephiroth himself that he deeply respect this Professor Gast, of which we currently know nothing, and considers Hojo to be a charlatan. The research he read to spurn him to action is something that Professor Gast carried out.
Do you think Sephirot's reaction might have been different if he found the exact same information he did, but it was penned by Hojo rather than Gast? After all, the only thing we know of Gast is that he's dead, so in story-writing terms, the authors could have made the story less complex by simply having Hojo, already a detestable figure, be the one responsible for the research that sent Sephiroth spiraling into madness. The only thing lost would be a bit of Sephiroth's characterization, in that then for the story to work he'd have to show, if not respect, at least not a lack of belief in Hojo's credentials as a scientist. Gast is extraneous detail adding complexity to an already complicated piece of backstory.
So... why do you think the writers decided to go with this specific tack on the scene, creating an already dead character just to give Sephiroth characterization? Do you think it adds enough to the scene to justify its existence?
I know, this is more about narrative in general than FFVII in specific, but it's something I think is really important when discussing Sephiroth's characterization, which has been the focus of these last few updates, so I'd like to hear your take on the matter while it's still fresh in your mind.