Sometimes I suspect that there are two prototypes of philosophers who write about humans - I call them "celestials" and "terrestrials", without implying that celestials have their heads in the clouds or that terrestrials have theirs buried in the ground. The difference between these two types is not so much in their theories but in whether or not they would find it a very sad thing if it turned out that the only way a human is superior to a wolf is this: the human brain is significantly more capacious and complex.