Like all people, Albert Einstein made mistakes, and like many physicists he sometimes published them. For most of us, the times when we go astray are happily forgettable. In Einstein's case, even the mistakes are noteworthy. They offer insight into the evolution of his thinking and with it the surrounding shifts in scientific conceptions of the universe. Einstein's errors also lay bare the challenges of discovery at the leading edge. When pushing the limits of understanding, it is difficult to know whether ideas written down on paper correspond to real phenomena and whether a radically new idea will lead to profound insights or will fizzle out.