Nietzsche classified humankind as «furtive».

«Don't tie yourself to furtive race of humans», he wrote.

And furtive, because he considered that human gender was a bridge, a medium, which takes it from the «animal condition» to a superior one: the Übermensch, the Super-Humankind.

Being this one, by its own side, a bridge, a passage, between «human condition» and the «divinity».

Furtive is the action that comes and soon goes just as it came. And that's why one says that a thief does what he does or acts like that.

I add that it is doubly furtive – it's also that, as a NATURAL thing that it is (every individualized thing, among the natural things, is a simple passage, a transition, even considering a person or a stone).