The death and destruction from the fertilizer plant that blew up in Texas looks a lot worse than the Boston Marathon bombings. But a random accident just doesn't inspire the terror that an act of terror does. We wonder if there are other terrorists lurking out there. Industrial accidents don't lurk; they just happen.
I wonder how often incidents like the ricin letters happen. Is this a rare event that just happens to have occurred about the time of the Boston bombings? Or do things like that happen all the time, and this one just came to people's attention because it happened so close to the bombing?