Behind you, you hear the screeching of brakes. You look up to see a car careening off the road. It mounts the sidewalk, narrowly misses two pedestrians and like some old Keystone Cops movie, crashes to an ignominious halt in a vegetable stand, a cloud of steam and smoke rising upwards. You look through the window to see what kind of idiot was responsible for this mess and you see the unmistakable features of a chimpanzee grinning back at you. When a person lets his physical side dominate him, he's allowing the monkey into the driver's seat.
Monkeys make good pets.
They're entertaining, they smile a lot, but you can't let them drive your car around town. A human being is a miraculous combination of body and soul. The body comes from the lower elements. The soul from on high. From these two disparate elements, Hashem creates a miraculous coexistence called Man.