Septimus's Jump

Septimus finds himself jumping to his death when approached by human nature in the form of Dr. Holmes. We know that he's already threatened to kill himself once, but Woolf never quite gives a reason- insane or otherwise- as to why he wants to end his life. In the end, it seems somehow connected to Holmes's appearance; perhaps he simply doesn't want to face Holmes's gregarious buck-upitude? Or perhaps he doesn't want to be rest-cured? That doesn't square, however, with the feel that we get in earlier references to the suicide he's threatening, because I, at least, got the impression that he was going to kill himself out of some kind of crazy theory- so that he'd arise jesus-style  because "there is no death"? At any rate, it certainly doesn't seem like Septimus is depressed earlier in the novel, because he marvels at such great length about the beauty around him and so forth. He's at a disconnect, certainly, and I could see him killing himself for either reason- so perhaps it's both? Had Holmes not shown up, would Septimus still have jumped at that moment? If he'd been in a more rational state of mind at the time (I, at least, got the impression that he'd already slipped out of the Old-Septimus groove he got into with Rezia for a bit) would he still have chosen to escape human nature?