Physicists through the ages have looked for an explanation for the behaviour of fundamental particles and forces within a single framework that would reveal the simplicity and power of the principles on which the functions and structures of the universe are based. There are a number of assumptions underlying this ongoing search, and their origins can be traced to the beginnings of Greek philosophy. The first is that there is a basic structure to the universe embodied in “laws of nature”. Secondly, these are accessible to human reason, so that the solution to the problem of finding a theory that would unite so much diversity, and account for what is permanent through change, is within our grasp. Thirdly, progress is made through criticism and adaptation of what has gone before, and with these continual advances an ever more accurate story is told. Finally, however, there is the “axiom of undecideability”: that there may be an ever closer approximation to certainty but, given our impermanent and contingent state, the struggle cannot succeed. Scientific advance is achieved by the continual replacement of one theory by another that is more probable than its predecessor, through a combination of brilliant intuition and the careful application of research (which the Greeks called historia). The results at each stage provide the stimulus for subsequent achievements in an ongoing and open-ended exploration of what exists now, and how such things came to be.