I'm not sure if my syntax is correct - I'm trying to say something that would correspond to German pattern je... desto. So:
The more difficult it is to define a notion, the higher are chances it would take the form of a woman.
EDIT wow, it never occurred to me that my meaning would come across as sexist. After reading the comments, I'd better explain what I wanted to say - thank you for pointing that out to me! I wanted to say that if you have a vague idea of something (like freedom, justice, goodness, etc.), it is most likely that philosophy and/or history has personified it as a woman. I hope that helps.