Some considerable discussions are spent in Hassidus covering the idea that people have two inclinations, an animal force and a human/spiritual/G-dly force, and the conflicts between the two.
I was somewhat surprised to find an article in Fortune Magazine presenting recent brain science proving this uniquely human conflict...
...What they found when they put Princeton undergraduates through these paces a year ago, with actual gift certificates at stake, was that we humans are of two minds. The calculating, cognitive, most advanced parts of the brain like the prefrontal cortex were hard at work computing and weighing options no matter what the students chose. But when they opted for the money now, something else happened. The more primitive limbic system, common to all mammals and associated with emotion and quick reactions, lit up as if it smelled dinner.
Cool article, read it here.