THE REEVE EFFECT.(actor Christopher Reeve's health)

The home of the actor Christopher Reeve is in the middle of horse country. He lives in Westchester County, down a winding country road that takes you past several estates with stables and riding tracks. At the end is a sprawling farmhouse set on a hill and surrounded by spruce and oak; a graded incline provides wheelchair access to the front door.

It has been eight years since Reeve broke his neck at an equestrian competition in Culpeper, Virginia. After his horse, Buck, stopped suddenly in front of an obstacle, Reeve flipped forward and suffered what doctors call a "hangman's injury": a fracture of the upper cervical vertebrae. Death by hanging often results from suffocation, and Reeve was heard to say, "I can't breathe."

The crushed vertebrae caused massive hemorrhaging within Reeve's upper spinal cord. The location of a spinal-cord injury determines its consequences. Indeed, a minute difference in the trajectory of Reeve's fall would have left him in dramatically different circumstances. An MRI scan that Reeve received after his accident suggested that if he had landed with his head onesixteenth of an inch to the left he would have died instantly. An impact slightly more to the right would have left him with a concussion, and he would have been back on his feet within weeks.

Reeve's injury left him paralyzed from the shoulders down. He was unable to breathe on his own, and doctors at a Virginia hospital immediately placed him on a ventilator. Reeve was informed that his injury was permanent, and that he would no longer feel sensation in ninety per cent of his body.

Upon arriving at Reeve's front door, I was greeted by an assistant--he employs several--and led to his office, where he sat waiting in his wheelchair. On a shelf behind him were pictures of his wife, Dana, and his three children, and a large blue button that read "proud yale parent." His daughter Alexandra is the captain of Yale's polo team. The Reeves are clearly not a superstitious family.

This spring, an experimental electrical-stimulation device was implanted in Reeve's diaphragm, and he now breathes without a respirator for hours at a time, so his speech has become more fluid and his voice more resonant. He gasped only occasionally. Reeve weighs two hundred and seventeen pounds and is six feet four, and even in his motorized wheelchair he looks imposing. The most striking change in his appearance has nothing to do with his accident. Reeve has alopecia areata, a condition that causes patchy hair loss, and in February he had his head shaved.

"I was told from the very start that it was hopeless, that it was impossible for me to regain movement below the shoulders," he began. "But every scientist should remove the word 'impossible' from his lexicon." Not only does Reeve want to cure himself; he is determined to transform medical research, which he feels is constrained by excessive caution. "Research should not be reckless," he said, but it does need to be fearless. "If you don't add courage to the equation, the scientific aspect will go to waste."