1. He is black. Geraldine Ferraro has a point: Obama's individual story is important and his racial makeup - he is of mixed race - is a part of his appeal. Black people have rallied to him.
2. He is not black. He is also the first black presidential hopeful to run as a post-racial candidate (hence the upset with Ferraro). White people feel unthreatened by him.
3. He was not taken seriously. Oops. If the Clinton people had blown him out in Iowa, at the beginning of the process, he would be toast.
4. He is serious. This appears to be a serious year, in which Americans are deeply worried about the state of the nation, and Obama's slightly professorial demeanour looks a good fit.
5. He offers self-help and self-improvement. She offered a plan to make America better - he offers a plan to make Americans themselves better.
6. He promises change in a year when Americans are ready for change.
7. He is 46 and handsome.
8. He catches the attention of the media but is a hard target to attack - you look uncool to diss him (as Hillary has discovered).
9. Mark Warner - the former governor of Virginia, the other young anti-Hillary man - didn't stand.
10. Axelrod wrote the script. David Axelrod was an adviser to The West Wing and helped mould the character (Matt Santos) who succeeded Jed Bartlett. He based him on Obama and now Obama seems based on Santos. But either way, it was written... And it has come to pass...