Where do major scientific breakthroughs come from? Do they arise from the logic of the scientific method, or do they result from flashes of genius? Are they the products of some mysterious zeitgeist, or spirit of the times, or do they emerge from chance or serendipity? Dean Simonton provides an answer, not by choosing one explanation and ignoring the others, but rather by unifying all four perspectives into a single theory in which chance plays the primary role, but with the significant involvement of logic, genius and zeitgeist.