Fundamental ideas play the most essential role in forming a physical theory. Books on physics are full of complicated mathematical formulae. But thought and ideas, not formulae, are the beginning of every physical theory. The ideas must later take the mathematical form of a quantitative theory, to make possible the comparison with experiment.
I have had to employ a fair number of technical concepts and use some mathematical operations, but the concepts have also been explained in non-technical terms and the mathematical results have been given intuitive explanation. It is hoped that the non-technical reader will not be put off by the formalities. The importance of the formal results lies ultimately in their relevance to normal communication and to things that people argue about and fight for.
-- Albert Einstein
— Amartya Sen, On Economic Inequality, p. vii