The call of the void: Why you feel the urge to jump off a cliff

This might sound a little weird to some of you, but have you ever been up somewhere really high, looked down and had the urge... to jump? And then you shudder, back away and go do something else. This urge probably came out of nowhere and disappeared as quickly as it came. Turns out, this urge has a name: the call of the void, or l'appel du vide in French. Some people feel it, some don't. To this day, there is no definite answer or explanation for the feeling but there are theories.