I have done some research about the maths and physics behind theoretical physics (i.e. string theory, which was mentioned in this forum earlier today) and it seems to me that in the cutting edge fields of study, like M-Theory, pure mathematics is as important as background knowledge in physics (am I wrong?). So my question is, is it more advisable to get to theoretical physics by a career path in mathematics or physics? Is it important to choose physics first, but not that relevant whether we choose maths or physics in grad school? I would like to hear your insights about this. Thanks in advance.