Why didn\'t the Romans conquer Scotland?

[Epictetus]

A: Crap weather that never takes the chill out of your bones, despite full days of sunshine every decade or so.

I know that is a joke, but in all honesty I think weather can be a factor to some extent. Marcus Aurelius' Meditations are filled with pinings for a nicer climate and angry self recriminations for wanting to live in a nicer place. I think it is human nature.