Einstein kept thinking about a unified theory and the nature of physical reality until the end of his life. Already in 1940, he foresaw the difficulties with which current string theorists struggle: “The two systems [general relativity and quantum theory] do not directly contradict each other; but they seem little adapted to fusion into one unified theory.” Then, just one month before his death, in 1955, at the age of seventy-six, he added some self-doubts: “It appears dubious whether a [classical] field theory can account for the atomistic structure of matter and radiation as well as of quantum phenomena.” Einstein did, however, find some comfort in the words of the eighteenth-century dramatist Gotthold Ephraim Lessing: “The aspiration to truth is more precious than its assured possession.” Blunders and all, perhaps no one in recent memory has aspired to truth more than Albert Einstein.

I would earnestly warn you against trying to find out the reason for and explanation of everything . . . To try and find out the reason for everything is very dangerous and leads to nothing but disappointment and dissatisfaction, unsettling your mind and in the end making you miserable.

—QUEEN VICTORIA

No scientific theory has an absolute and permanent value. As experimental and observational methods and tools improve, theories can be refuted, or they may metamorphose into new forms that incorporate some of the earlier ideas. Einstein himself stressed this evolutionary nature of theories in physics: “The most beautiful fate of a physical theory is to point the way to the establishment of a more inclusive theory, in which it lives as a limiting case.” Darwin’s theory for the evolution of life by means of natural selection was only strengthened through the application of modern genetics. Newton’s theory of gravity continues to live as a limiting case within the framework of general relativity. The road to a “new and improved” theory is far from smooth, and progress is definitely not a headlong rush to the truth. If luminaries such as Darwin, Kelvin, Pauling, Hoyle, and Einstein can commit serious blunders, imagine the scorecards of lesser scientists. When James Joyce wrote in Ulysses, “A man of genius makes no mistakes. His errors are volitional and are the portals of discovery,” he meant the first part of his comment to be provocative. As we have seen in this book, however, the blunders of genius are often indeed the portals of discovery.