A famous aphorism by Albert Einstein is carved in stone, in the original German, over the mantelpiece of one of the common rooms at Princeton. When I was a graduate student I would sometimes take refuge there – where, I was told, Einstein himself had held seminars. A shadow of his intellectual aura seemed to linger in the recesses of that darkly paneled space. The aphorism read, Raffiniert ist der Herr Gott, aber boshaft ist Er nicht, that is, “The Lord God is subtle but He is not malicious.”

The statement both intrigued and plagued me. Often, in the gloomy days that accompanied my doctoral toils, I would run my fingers along the stone letters of the saying, as though to draw encouragement and possible inspiration from his words. It intrigued me because of its symmetry. God’s subtlety – indeed, His refinement, His sophistication – stood in conjunction with his lack of malice. The first proposition appeared to me based not solely on Einstein’s personal conviction but on the bedrock of his scientific intuitions and insights. The second proposition, however – by its nature more tenuous – struck me as an expression of hope, of faith even. In its elegance Einstein’s maxim embodied an equipoise of certainty and belief.

The statement plagued me because at that time I was undergoing the ordeal of researching and writing a doctoral dissertation on the very subject of Einstein’s aphorism. Plunged into the thorny texts of ancient and Medieval thinkers – Christian, Jewish, and Muslim – I was studying the question of whether this is the best of all possible worlds. Einstein’s dictum, which balanced science and metaphysics, might have been formulated by any of those philosophers from a long-discarded tradition.

This month marks the centenary of the amazing year in which Einstein published, in close succession, five scientific papers that would change our notion of reality forever; it also marks the 50th anniversary of his death. It’s probably as difficult – that is to say, as impossible – to elucidate the origins of the insights that led Einstein to discover the nature of light or the special theory of relativity as it would be to pinpoint the genesis of a Mozart symphony or a painting by Velazquez. For it seems likely his intuitions emerged in the same profound and ultimately incomprehensible way that the highest works of art emerge, rather than purely from mathematical computation.

In his new book, “Einstein 1905: The Standard of Greatness” (Harvard University Press, 173 pages, $21.95), the physicist John S. Rigden takes us month by month through that incredible year, beginning in March 1905 with Einstein’s paper on the quantum nature of light and concluding in September with his formulation of “E=mc2,” the one formula that everyone in the world can recognize, if not understand.

Mr. Rigden is very good at evoking the vehement debates that took place over Einstein’s findings. In 1905, for example, all physicists held that light was a wave; there was stubborn resistance to Einstein’s “particle model.” Max Planck could declare, even eight years later, “that sometimes, as for instance in his hypothesis on light quanta, he may have gone overboard in his speculations should not be held against him too much.” So entrenched was scientific “orthodoxy” on this point that even in 1916, when Robert Millikan confirmed Einstein’s theory, he could not accept the results of his own experiment and continued to characterize the quantum theory of light as “a bold, not to say reckless, hypothesis” which “has now been pretty much abandoned.”

When Niels Bohr in the course of his 1922 Nobel Prize acceptance speech discounted the theory, Einstein remained unfazed. And Bohr in fact was wrong. One year later, Arthur Compton conducted experiments that decisively vindicated Einstein; in Mr. Rigden’s words, Compton “discovered that when X-rays ‘hit’ an electron, a collision occurs that is exactly like the collision between two billiard balls.” It had taken 17 years for the greatest scientific minds to accept the reality of the photon.

The portrait of Einstein that emerges from Mr. Rigden’s account is as compelling as his theories. C.P. Snow captured his most striking trait when he remarked that Einstein was “unbudgeable.” Time and again, unshaken by criticism, he calmly waited for experimental evidence to prove him correct. Never was the maxim “Genius is a long patience” truer than in his case.

In fairness, of course, the underlying weirdness of physical reality, as shown by Einstein’s discoveries, dismayed his critics. Not only the famous slowing of clocks or the bending of light by the curvature of space or the very equivalence of energy and mass, but other still zanier phenomena. Here is how Einstein himself postulated one such in 1933:

Suppose two particles are set in motion towards each other with the same, very large, momentum, and that they interact with each other for a very short time when they pass at known positions. Consider now an observer who gets hold of one of the particles, far away from the region of interaction, and measures its momentum; then, from conditions of the experiment, he will obviously be able to deduce the momentum of the other particle. If, however, he chooses to measure the position of the first particle, he will be able to tell where the other particle is. This is a perfectly correct and straightforward deduction from the principles of quantum mechanics; but is it not paradoxical? How can the final state of the second particle be influenced by a measurement performed on the first, after all physical interaction has ceased between them?

Mr. Rigden explains: “When an atom goes from a higher to a lower energy state, it can emit two photons, which fly away from the atom in opposite directions. If at some time in the future a measurement is made on one photon, thereby changing it, the second photon, halfway across the universe, will change instantaneously. That something happening in one place can instantly affect what happens in another place Einstein called ‘spooky.’ It violated his view of causality.”

A decade after Einstein’s death, this eerie effect was explained as the result of “entanglement.” Despite their immense distance from each other, the photons are not truly autonomous from one another but “entangled.” But is this really an “explanation?” Doesn’t such entanglement only deepen the puzzle? And, scientific simpleton that I am, I’d like to know how we detect the parallel change in the second photon without measuring, and so further changing, it as well.

Einstein spent his later career attempting to reconcile his “unbudgeable” sense of the order of reality with quantum mechanics, the very science he had himself helped to engender. Quantum mechanics appears to suggest something random, something mischievously undiscoverable, in the design of the cosmos. In this light, how could Einstein have been so sure that the Lord God is not malicious? Is it true to say that if God is subtle, then He isn’t – perhaps cannot be – malicious, as though subtlety presupposed goodness, implied justice?

My Medieval thinkers emphasized God’s sovereign simplicity, not his sophistication; like us, they associated goodness with simplicity, malice with subtlety. Yet could there be a subtlety of goodness in those very laws of the universe that Einstein, suspended between certainty and hope, struggled all his life to identify and define?