Since the 29-year-old intelligence contractor Edward Snowden outed himself as the source of the NSA leaks on Sunday, reporters and pundits—heck, even Snowden himself—have compared him with Bradley Manning, the Army private on trial for passing classified material about the Iraq and Afghanistan wars to Wikileaks. There’s obviously something to the comparison—both men were apparently dedicated enough to the cause of transparency to risk their lives for it. But, after reading the early biographical reporting about Snowden, I can’t help recalling another transparency activist in the news recently: Aaron Swartz, who committed suicide in January while awaiting trial for downloading millions of pages from JSTOR, the online database of academic articles.

Both Snowden and Swartz (and, for that matter Manning) were precociously talented computer programmers who were frustrated in classroom settings—neither completed high school or college—but easily assimilated knowledge on their own. Both had strong moral and idealistic streaks, along with (apparently) well-worked out, libertarian-ish, ideas about the proper relationship of government to its citizens. Both had high hopes for Barack Obama, but became disillusioned with his administration relatively quickly.

And yet both come off as basically liberal in their outlook, as opposed to anarchist or some other form of radical. Snowden told The Guardian there was a key difference between himself and Manning: "There are all sorts of documents that would have made a big impact that I didn't turn over, because harming people isn't my goal. Transparency is." (Manning observed no such restraints.) Swartz, according to several friends I interviewed for this profile, likewise believed that Wikileaks went too far in releasing information that could do more harm than good. He worried that the group had become an exercise in showmanship and preening.

Now, clearly, there are key differences between Snowden and Swartz. Even though Swartz was facing the prospect of decades in prison, the act that got him in trouble couldn’t have been more than a minor offense under any rational legal code. (JSTOR articles are available to anyone with access to a university or research library; JSTOR itself declined to pursue the case.) By contrast, it’s obvious that Snowden, whether you agree or disagree with his decision to distribute classified material, has undertaken something of enormous legal consequence.

But whatever their differences, I think Swartz sheds light on the key mystery in Snowden’s psycho-profile. If, like Swartz, Snowden really was a liberal rather than a radical, how did he end up driven to such extremes?