In the final weeks of his life, Albert Einstein learned of the death of his old physicist friend Michele Besso from his Zurich student days six decades before. “He has departed from this strange world a little ahead of me,” Einstein wrote to the Besso family. “That means nothing. For us believing physicists, the distinction between past, present, and future is only a stubborn illusion.”

What did Einstein mean by “us believing physicists”? Did he mean belief in the models of theoretical physics that make no distinction between past, present, and future? Did he mean belief in some impersonal force that exists above such time constraints? Was he just being polite and consoling? Who knows? Such is the enigma of the most well-known scientist in history, whose fame was such that nearly everything he wrote or said was scrutinized for its meaning and import. It is easy to yank his words out of context and spin them in any direction. Without a rich personal context in which to situate Einstein’s thoughts and theories, it is hard to know for sure how to nuance his utterances. Until now.

Thanks to the Einstein Papers Project under the direction of Diana Kormos Buchwald at the California Institute of Technology in Pasadena, Calif., the archival materials are now available to tell the full story, and Walter Isaacson has written a narrative masterpiece that merges into a seamless whole two worlds that are usually separated by a great divide — scientific exposition and literary style. This is a great read by a great writer about a great man — a biographical perfect storm.

Mr. Isaacson recounts the wellworn stories about Einstein’s youthful rebelliousness against his early teachers and their insistence that education is best imparted through rote drills and the memorization of countless factoids, as well as the famous story about the teacher who declared that the young Einstein would never amount to much. “From his boyhood on Einstein understood that freedom of thought is the key to imagination,” Mr. Isaacson writes, “and, as he famously declared, ‘imagination is more important than knowledge.'”

Yes, well, you do need to know what the facts are before you overturn them, and it helps to have Einstein’s imaginative skills if you wish to challenge the likes of Isaac Newton. You and I may have dreams about what it would be like to ride alongside a beam of light (time appears to stop) or imagine what it means to play catch in a free-falling elevator (you, your partner, and the ball would all be “weightless” in a “zero-gravity” environment relative to the freefalling frame of reference), but it takes an Einstein to translate a thought experiment into meaningful mathematical equations, and then employ those equations to challenge the very nature of space and time. But, as Mr. Isaacson shows, Einstein had just such a mind that allowed him to puzzle over commonplace things (like light beams and elevators) and incorporate them into his most uncommonplace theories.

As well, Mr. Isaacson stitches together the loose patches of Einstein’s personal life, most notably his problematic relationship with women that could best be described as, well, problematic. The best shot he had at enjoying an equal, loving partnership was with his fellow physicist Mileva Maric, a Serbian three years his senior but close to his equal intellectually (to the extent that anyone was). But that unraveled under the strain of having an illegitimate daughter who was put up for adoption, marriage, and the rearing of two boys for which Mileva bore the brunt of the work, and Einstein’s inability to land an academic position (settling for the patent clerk job during which he experienced his annus mirabilis of 1905 when he produced four papers in five months, any one of which would have been a career topper for most scientists but was just the beginning for Einstein).

To get Maric to agree to a divorce, Einstein had to promise her the money from his Nobel Prize that, he assured her, would eventually be his. (She collected in 1922 and purchased three apartment buildings in Zurich with the money.) In the meantime, she had to agree to a list of cruel conditions that included “you will not expect any intimacy from me, nor will you approach me in any way,” “you will stop talking to me if I request it,” “you will leave my bedroom or study immediately without protest if I request it,” all while she was instructed to do his laundry, serve him three meals a day, and keep his bedroom and study neat. Maric was a toughminded personality, the treatment of a fellow physicist as if she were a charwoman reveals a darker side to Einstein’s personality.

Which brings us back to God, the universe, and everything. Einstein matters not just because of his science, which was spectacularly important in his own time and in ours, but because of how he connected his science to the politics of his time and the religion of all time. Einstein’s Jewish identity was undeniably important to all aspects of his life, especially his politics (“My relationship to the Jewish people has become my strongest human tie,” he wrote after declining the presidency of Israel). And the religiosity of his childhood still compelled him in midlife: “Try and penetrate with our limited means the secrets of nature and you will find that, behind all the discernible laws and connections, there remains something subtle, intangible and inexplicable. Veneration for this force beyond anything that we can comprehend is my religion. To that extent I am, in fact, religious.”

Being religious in some esoteric sense of the awe and wonder over the cosmos is one thing, but what about God? When he turned 50, Einstein granted an interview in which he was asked point-blank, whether he believed in God. “I am not an atheist,” he began. “The problem involved is too vast for our limited minds. We are in the position of a little child entering a huge library filled with books in many languages. The child knows someone must have written those books. It does not know how. It does not understand the languages in which they are written. The child dimly suspects a mysterious order in the arrangement of the books but doesn’t know what it is. That, it seems to me, is the attitude of even the most intelligent human being toward God. We see the universe marvelously arranged and obeying certain laws but only dimly understand these laws.”

To a Colorado banker who wrote and asked him the same question, Einstein responded: “I cannot conceive of a personal God who would directly influence the actions of individuals or would sit in judgment on creatures of his own creation. My religiosity consists of a humble admiration of the infinitely superior spirit that reveals itself in the little that we can comprehend about the knowable world. That deeply emotional conviction of the presence of a superior reasoning power, which is revealed in the incomprehensible universe, forms my idea of God.”

Finally, in what has become the iconic answer to the God question, Einstein was instructed to compose a statement of 50 words in a telegram. Einstein did it in 32: “I believe in Spinoza’s God, who reveals himself in the lawful harmony of all that exists, but not in a God who concerns himself with the fate and the doings of mankind.” Fortunately for us, Einstein concerned himself with the fate and doings of the universe, and mankind is richer because of him.

Mr. Shermer is the publisher of Skeptic magazine (www.skeptic.com), a monthly columnist for Scientific American, and the author of “How We Believe and the Science of Good and Evil.” His latest book is “Why Darwin Matters.”