Course an incubator isn't "nature" but the type of hens I have won't set a clutch of eggs, it's just been bred out of them. They're egg producing machines, but they have no interest in setting them.
sorry - I was reading this one & remembered this:
http://www.youtube.com/watch?v=RQtkgr3XD8w
I blame not enough sleep & a long-trip weekend..