Something I've noticed while browsing book stores/libraries is that it is remarkably more difficult to find literature on parabolic PDEs than elliptic. For example check Amazon:
226 vs 427 results. And for good measure, hyperbolic:
Why is there such a huge discrepancy? Why are there almost double the amount of elliptic texts than parabolic? Both types have very important examples. Are elliptic easier to write about or more interesting? Is there more theory? Why the difference? Also why are hyperbolic in the middle?