Only very, very rarely does someone so far out of the political swim as Jerry Brown, who last held political office almost a decade ago, manage to win the presidential nomination of a major party.

• 像布朗这样远离政海——他最后一次从政几乎是十年以前的事——而能设法赢得主要政党提名竞选总统，实在是一件绝无仅有之事。