Following Kamerlingh Onnes’ discovery of zero resistance, it took a very long time to understand how superconducting electrons can move without hindrance through a metal. Attempts to explain from first principles how superconductivity comes about proved to be one of the most intractable problems of physics. Progress required more than just new data; it needed an innovative theoretical framework built around radical new ideas. There are inherent difficulties in achieving this. Fundamentally new concepts are not discovered by observation alone but require new modes of imaginative thought, which by their very nature are unpredictable and elusive.