The great firewall of China
The blog's on and off. One thing you might not be too clear on about China's Great Firewall - something that almost everyone seems to miss - is that it's not closely controlled by serious government officials poring over everyone's website, tut-tutting and pushing the 'block' button. It's a very nebulous and disorganised affair controlled by putsters on a wage who don't care very much about it, and with only the vaguest guidelines as to what's in public interest to block.
The fact that your blog gets censored at times, and not at others, has nothing to do with any particular article you may have written - the firewall generally blocks vast chunks of the Internet, without particularly worrying about whether it's a reasonable concern or not - and your blog may never have in fact been reviewed at all. Likewise, the blocking of the Marxist archive site is very unlikely to be the result of some hardnosed official deciding the site's just too dangerous to allow people to read, but of some 20something cheap graduate in the government's employ with an exaggerated ability in English sitting at his computer one day worrying that he hasn't met his month's blocking quota, and putting the site - or perhaps the whole domain - on his list as a result.
That's the reality behind China's totalitarian control of the Internet. Indifference.