THE SCIENCE ROOM WAS on the second floor. Robert Neville's footsteps thudded hollowly up the marble steps of the Los Angeles Public Library. It was April 7, 1976.

It had come to him, after a half week of drinking, disgust, and desultory investigation, that he was wasting his time. Isolated experiments were yielding nothing, that was clear. If there was a rational answer to the problem (and he had to believe that there was), he could only find it by careful research.

Tentatively, for want of better knowledge, he had set up a possible basis, and that was blood. It provided, at least, a starting point. Step number one, then, was reading about blood.

The silence of the library was complete save for the thudding of his shoes as he walked along the second-floor hallway. Outside, there were birds sometimes and, even lacking that, there seemed to be a sort of sound outside.

Inexplicable, perhaps, but it never seemed as deathly still in the open as it did inside. a building.

Especially here in this giant, gray-stoned building that housed the literature of a world's dead. Probably it was being surrounded by walls, he thought, something purely psychological. But knowing that didn't make it any easier. There were no psychiatrists left to murmur of groundless neuroses and auditory hallucinations. The last man in the world was irretrievably stuck with his delusions.

He entered the Science Room.

It was a high-ceilinged room with tall, large-paned windows. Across from the doorway was the desk where books had been checked out in days when books were still being checked out.

He stood there for a moment looking around the silent room, shaking his head slowly. All these books, he thought, the residue of a planet's intellect, the scrapings of futile minds, the leftovers, the potpourri of artifacts that had no power to save men from perishing.

His shoes clicked across the dark tiles as he walked to the beginning of the shelves on his left. His eyes moved to the cards between the shelf sections. "Astronomy," he read; books about the heavens. He moved by them. It was not the heavens he was concerned about. Man's lust for the stars had died with the others. "Physics," "Chemistry," "Engineering." He passed them by and entered the main reading section of the Science Room.

He stopped and looked up at the high ceiling. There were two banks of dead lights overhead and the ceiling was divided into great sunken squares, each square decorated with what looked like Indian mosaics. Morning sunlight filtered through the dusty windows and he saw motes floating gently on the current of its beams.

He looked down the row of long wooden tables with chairs lined up before them. Someone had put them in place very neatly. The day the library was shut down, he thought, some maiden librarian had moved down the room, pushing each chair against its table. Carefully, with a plodding precision that was the cachet of herself.

He thought about that visionary lady. To die, he thought, never knowing the fierce joy and attendant comfort of a loved one's embrace. To sink into that hideous coma, to sink then into death and, perhaps, return to sterile, awful wanderings. All without knowing what it was to love and be loved.

That was a tragedy more terrible than becoming a vampire.

He shook his head. All right, that's enough, he told himself, you haven't got the time for maudlin reveries.

He bypassed books until he came to "Medicine." That was what he wanted. He looked through the titles. Books on hygiene, on anatomy, on physiology (general and specialized), on curative practices. Farther down, on bacteriology.

He pulled out five books on general physiology and several works on blood. These he stacked on one of the dust-surfaced tables. Should he get any of the books on bacteriology? He stood a minute, looking indecisively at the buckram backs.

Finally he shrugged. Well, what's the difference? he thought. They can't do any harm. He pulled out several of them at random and added them to the pile. He now had nine books on the table. That was enough for a start. He expected he'd be coming back.

As he left the Science Room, he looked up at the clock over the door.

The red hands had stopped at four-twenty-seven. He wondered what day they had stopped. As he descended the stairs with his armful of books, he wondered at just what moment the clock had stopped. Had it been morning or night? Was it raining or shining? Was anyone there when it stopped?

He twisted his shoulders irritably. For God's sake, what's the difference? he asked himself. He was getting disgusted at this increasing nostalgic preoccupation with the past. It was a weakness, he knew, a weakness he could scarcely afford if he intended to go on. And yet he kept discovering himself drifting into extensive meditation on aspects of the past. It was almost more than he could control, and it was making him furious with himself.

He couldn't get the huge front doors open from the inside, either; they were too well locked. He had to go out through the broken window again, first dropping the books to the sidewalk one at .a time, then himself. He took the books to his car and got in.

As he started the car, he saw that he was parked along a red-painted curb, facing in the wrong direction on a one-way street. He looked up and down the street.

"Policeman!" he found himself calling. "Oh, police- man!"

He laughed for a mile without stopping, wondering just what was so funny about it.

He put down the book. He'd been reading again about the lymphatic system. He vaguely remembered reading about it months before, during the time he now called his "frenzied period." But what he'd read had made no impression on him then because he'd had nothing to apply it to.

There seemed to be something there now.

The thin walls of the blood capillaries permitted blood plasma to escape into the tissue spaces along with the red and colorless cells. These escaped materials eventually returned to the blood system through the lymphatic vessels, carried back by the thin fluid called lymph.

During this return flow, the lymph trickled through lymph nodes, which interrupted the flow and filtered out the solid particles of body waste, thus preventing them from entering the blood system.

Now.

There were two things that activated the lymphatic system: (1) breathing, which caused the diaphragm to compress the abdominal contents, thus forci............