Instead of encouraging online service providers to blacklist sites and writing new espionage laws that would further criminalize the publication of government secrets, we should regard WikiLeaks as subject to the same first amendment rights that protect The New York Times. And as a society, we should embrace the site as an expression of the fundamental freedom that is at the core of our Bill of Rights, not react like Chinese corporations that are happy to censor information on behalf of their government to curry favor.
The phrase is a simple observation, like saying “a compass wants to point north”. Information intrinsically has a tendency to spread. Controlling information, bottling it up and keeping it limited, is difficult. There's a bit of a poetic turn in saying “wants”, since of course information has no agency. The underlying truth is really a statement about human nature; people tend to share information.
Also along these lines: "There are no secrets, only information you don't yet have."