Tom climbs out onto the ledge to retrieve a sheet of paper he thinks is very important and because he doesn't realize, until he gets out there, how great a risk he is taking. The author Jack Finney takes pains to show the importance of the piece of paper in order to make it plausible that Tom would risk going after it.
It was hard for him to understand that he actually had to abandon it--it was ridiculous--and he began to curse. Of all the papers on his desk, why did it have to be this one in particular! On four long Saturday afternoons he had stood in supermarkets counting the people who passed certain displays, and the results were scribbled on that yellow sheet. From stacks of trade publications, gone over page by page in snatched half-hours at work and during evenings at home, he had copied facts, quotations, and figures onto that sheet. And he had carried it with him to the Public Library on Fifth Avenue, where he'd spent a dozen lunch hours and early evenings adding more. All were needed to support and lend authority to his idea for a new grocery-store display method; without them his idea was a mere opinion. And there they all lay in his own improvised shorthand--countless hours of work--out there on the ledge.
Jack Finney spends five full paragraphs describing Tom's mixed feelings about taking the risk and eventually talking himself into climbing out the window. Tom convinces himself that the danger is not too serious as long as he doesn't look down--but he knows that if he does look down, the sight of the street eleven floors below could not only make him dizzy but could paralyze him with fear.
The ledge is narrower than he expected. It is not even as wide as his foot. He is standing on the balls of his feet with his heels sticking out over empty space. He keeps his body glued against the brick wall and shuffles sideways for about five yards without looking down. But he didn't anticipate the difficulty he would have just in picking up the sheet of paper. He can't bend his knees enough to lower his arm so that his fingertips can reach the paper. His knees are pressing against the brick wall and forcing his body backward over the abyss. And he is forced to look down at the paper in order to get a grip on it.
He saw, in this instant, the Loew's theater sign, blocks ahead past Fiftieth Street; the miles of traffic signals, all green now; the lights of cars and street lamps; countless neon signs; and the moving black dots of people. And a violent instantaneous exlosion of absolute terror roared through him.
He is paralyzed with fright. He feels positive he is going to die out there. When a man is facing death he is sure to reflect upon how he lived his life, his mistakes and regrets. There are many literary works that deal with this human experience. Famous examples include Tolstoy's "The Death of Ivan Ilyich," Arthur Miller's Death of a Salesman, Ambrose Bierce's "An Occurrence at Owl Creek Bridge," and Albert Camus's The Stranger. Tom Benecke realizes he was attaching too much importance to success in the wholesale grocery business and not appreciating his home and loving wife. The thought of Clare gives him courage to start creeping back until he reaches the lighted window of his warm and cozy little home. He can look inside and remember how safe and happy he had felt there, but the window panel has slammed shut and he still has to find some way of getting back inside.