There was almost a religious reverence in the hush that descended upon the audience at the beginning of a Stephen Hawking lecture. Typically, every seat was taken, and if the fire marshals weren’t a force to be reckoned with, there were large clots of people near the exits and in the aisles, craning their necks to get their first view of the physicist. And as he wheeled out onto stage, the audience was palpably awed. "Sometimes there were 30 or 40 seconds of pure silence," says Christophe Galfard, one of Hawking's graduate students who himself became a popularizer of science. "For me, it was the silence that made it so ... that's what triggered my wish to pursue that road."

But despite Hawking's passion for sharing his work in cosmology and astrophysics with the public, few in the audience were there to learn about his science. They were there to be in the presence a person who had ascended Mount Sinai and been granted a glimpse of the secrets of the cosmos. Hawking was a great scientist, but in his quest for recognition, he took on the mantle of a prophet. It was a Faustian bargain that made Hawking the preeminent scientist of our lifetimes—but at a cost.

When a prophet speaks, he speaks with all the confidence and infallibility of divine revelation. Yet a scientist's trade, the very fabric of his profession, is uncertainty. Almost by definition, a biologist or a physicist or a chemist has a head filled with inaccurate information; even those with the biggest egos realize that much of the knowledge they’ve built up over the years is tentative, incomplete or even outright wrong. Indeed, the scientist's whole purpose is to reduce that uncertainty by just a little bit. While prophets are always right, good scientists, trained to strive to be a little less wrong, are by nature tentative and conditional. And this makes them easy to ignore even when they're the only kind of authorities that count.

Not Stephen Hawking. Once he assumed the mantle of a prophet in the late 1980s, Stephen Hawking would never be ignored. His books were all but guaranteed to sell, whether or not they were well written or even comprehensible. His lectures were typically sold out, with hopefuls packing the aisles to try and get a better look at the famous physicist. He could command an audience like no other scientist; the press and the public would hang on his every word—even when those words didn't have anything to do with his work on black holes or cosmology, or even betray any deep insight or knowledge.

Hawking managed to convince the public that his opinion always mattered. "[H]is comments attracted exaggerated attention even on topics where he had no special expertise," wrote Martin Rees, a close friend and colleague of his, "for instance philosophy, or the dangers from aliens or from intelligent machines." His overweening confidence—and his stubbornness—cost him respect from many of his colleagues, especially late in his career.

Perhaps the most difficult aspect of Hawking's transformation into a celebrity, however, was entangled with his disability. Just as he began to make himself known on the physics circuit, his disease (amyotrophic lateral sclerosis, also known as Lou Gehrig's disease) began to bite. Hawking always suspected that his quick rise through the physics ranks, his early awards, his appointment to the Royal Society at the tender age of 32—even his appointment to the Lucasian chair that Isaac Newton held several centuries before him—all resulted from his disability rather than his physics prowess. “I think I was appointed as a stopgap to fill the chair as someone whose work would not disgrace the standards expected of the Lucasian chair, but I think they thought I wouldn’t live very long, and then they could choose again, by which time they could find a more suitable candidate,” he once told an interviewer. “Well, I’m sorry to disappoint the electors.”

As much as this doubt nagged at Hawking throughout his life—he truly wanted to be recognized for his science rather than for his perserverance in the face of disability—Hawking realized that his celebrity, if not his physics, was founded on the latter as much as the former. It disturbed him that his outsized reputation was due to the caricature of him a disabled genius—that he was viewed as a seer gifted with extraordinary insight in compensation for a bodily incapacity. But at the same time, he embraced it and even helped build the myth to increase his renown.

The cost to Hawking was that the myth obscured the humanity of the person behind it. In truth, Hawking was not the greatest scientist of our time. He was an important physicist whose importance is almost universally misunderstood; a person who suffered deeply and also caused deep suffering; a celebrity scientist who broke the mold of his forebears and fundamentally changed the concept of a scientific celebrity. To truly understand Hawking—just as to truly understand science—one has to reject the myth and examine the messy reality underneath. To stop looking at Hawking as a prophet, but instead as a flawed and brilliant human being.