THE TIME OF YEAR arrived when Miss celebrated her birthday. Andrew had already learned that one's birthday celebration was an important event in the annual round of human life-a commemoration of the anniversary of the day that one had emerged from one's mother's womb.

Andrew thought that it was strange that humans would choose the day of coming forth from the womb as the significant thing to commemorate. He knew something of human biology, and it seemed to him that it would be much more important to focus on the moment of the actual creation of the organism, when the sperm cell entered the ovum and the process of cell division began. Surely that was the real point of origin of any person!

Certainly the new person was already alive-if not yet capable of independent functioning-during the nine months spent within the womb. Nor was a human being particularly capable of independent functioning immediately after leaving the womb, so the distinction between birth and pre-birth that humans insisted on drawing made very little sense to Andrew.

He himself had been ready to perform all his programmed functions the moment the last phase of his assembly was complete and his pathways had been initialized. But a newborn child was far from able to manage on its own. Andrew could see no effective difference between a fetus that had completed its various stages of fetal development but was still inside its mother and the same fetus, a day or two later, that had emerged. One was inside and one was outside, that was all. But they were just about equally helpless. So why not celebrate the anniversary of one's moment of conception instead of the anniversary of one's release from the womb?

The more he pondered it, though, the more he saw that there was some logic to either view. What, for example, would he select as his own birthday, assuming that robots felt any need to celebrate their birthdays? The date when the factory had begun assembling him, or the date on which his positronic brain had been installed in its case and initialization of somatic control had been keyed? Had he been "born" when the first strands of his armature were being drawn together, or when the unique set of perceptions that constituted NDR-113 had gone into operation? A mere armature wasn't him, whatever he was. His positronic brain was him Or the combination of the positronic brain properly placed within the body that had been designed to house it. So his birthday

Oh, it was all so confusing! And robots weren't supposed to be plagued by confusion. Their positronic minds were more complex than the simple digital "minds" of non-positronic computers, which operated entirely in stark binary realms, mere patterns of on or off, yes or no, positive or negative, and that complexity could sometimes lead to moments of conflicting potential. But nevertheless robots were logical creatures who were able to find their way out of such conflicts, usually, by sorting the data in a sensible way. Why, then, was he having so much trouble comprehending this business of when one's birthday ought to be?

Because birthdays are a purely human concept, he answered himself. They have no relevance to robots. And you are not a human being, so you do not need to worry about when your birthday ought or ought not to be celebrated.

At any rate, it was Miss's birthday. Sir made a point of coming home early that day, even though the Regional Legislature was embroiled in some complicated debate over interplanetary free-trade zones. The whole family dressed in holiday clothes and gathered around the great slab of polished redwood that was the dining-room table and candles were lit, and Andrew served an elaborate dinner that he and Ma'am had spent hours planning, and afterward Miss formally received and opened her presents. The receiving of presents-new possessions, given to you by others-was apparently a major part of the birthday-celebration ritual.

Andrew watched, not really understanding. He knew that humans placed high importance on the owning of things, specific objects that belonged only to them, but it was very hard to comprehend what value most of those objects had for them, or why they placed such emphasis on having them.

Little Miss, who had learned how to read only a year or two before, gave her sister a book. Not a cassette, not an infodisk, not a holocube, but an actual book, with a cover and binding and pages. Little Miss was very fond of books. So was Miss-especially books of poetry, which was a way of writing things in cryptic phrases arranged in uneven lines that Andrew found extremely mysterious.

"How marvelous!" Miss cried, when she had taken her book from its gaily covered wrapper. "The Rubaiyat of Omar Khayyam! I've always wanted it! But how did you even know there was such a thing? Who told you about it, Amanda?"

"I read about it," said Little Miss, looking a trifle put out. "You think I don't know anything at all, just because I'm five years younger than you, but let me tell you, Melissa-"

"Girls! Girls!" Sir called warningly. "Let's have no bickering at the birthday dinner!"

The next present Miss opened was from her mother: a fine cashmere sweater, white and fluffy. Miss was so excited that she put it on over the sweater she was already wearing.

And then she opened the small package that was her father's gift, and gasped; for Sir had bought her an intricate pendant of pink ivorite, carved with marvelous scrollwork so delicately worked that even Andrew's flawless vision was hard pressed to follow all its curving and interlocking patterns. Miss looked radiantly happy. She lifted it by its fine golden chain and slipped it over her head, lowering it carefully until it lay perfectly centered on the front of her new sweater.

"Happy birthday, Melissa," Sir said. And Ma'am chimed in, and Little Miss too, and they all sang the birthday song. Then Ma'am called for another round of the song, and this time she gestured to Andrew, who joined in, singing along with them.

For a moment he wondered whether he should have given Amanda some sort of present also. No, he thought, she did not seem to have expected it from him. And why should she? He wasn't a member of the family. He was an item of household machinery. The giving of birthday presents was entirely a human thing.

It was a lovely birthday dinner. There was only one thing wrong with it, which was that Little Miss seemed bitterly envious of Miss's lovely ivorite pendant.

She tried to hide it, of course. It was her sister's birthday dinner, after all, and she didn't want to spoil it. But all during the course of the evening Little Miss kept stealing glances at the pendant that gleamed warmly in pink and gold atop Melissa's sweater, and it took no great subtlety of perception on Andrew's part to know how unhappy she was.

He wished there was something he could do to cheer her up. But this whole affair of birthdays, and presents, and sisters, and envy, and other such human concepts-they were really beyond his comprehension. He was a very capable robot of the kind that he was designed to be, but his designers had seen no need to give him the capacity to understand why one little girl would be upset about a beautiful object that had been given to another little girl who was her sister on the occasion of her birthday.

A day or two later, though, Little Miss came to Andrew and said, "Can I speak to you, Andrew?"

"Of course you can."

"Did you like that pendant that Daddy gave Melissa?"

"It seemed to be very beautiful."

"It is very beautiful. It's the most gorgeous thing I've ever seen."

"It is quite beautiful, yes," Andrew said. " And I am sure that Sir will give you something every bit as beautiful when it is the time of your birthday."

"My birthday is three months from now," Little Miss said.

She said it as though that were an eternity away.

Andrew waited, not quite able to determine where this conversation was heading.

Then Little Miss went to the cabinet where she had put the piece of driftwood that she had brought from the beach the day he had gone swimming, and held it out to him.

"Will you make a pendant for me, Andrew? Out of this?"

"A wooden pendant?"

"Well, I don't happen to have any ivorite handy. But this is very pretty wood. You know how to carve, don't you? Or you could learn, I suppose."

"I'm certain that my mechanical skills would be equal to the job. But I would need certain tools, and-"

"Here," said Little Miss.

She had taken a small knife from the kitchen. She handed it to him with an air of great gravity, as if she were giving him a whole set of sculptor's blades.

"This should be all you need," she said. "I have faith in you, Andrew."

And she took his metal hand in hers and gave it a squeeze.

That night, in the quiet of the room where he usually stored himself when his day's chores were done, Andrew studied the piece of driftwood with great care for perhaps fifteen minutes, analyzing its grain, its density, its curvature. He gave the little knife careful scrutiny too, testing it on a piece of wood he had picked up in the garden to see how useful it would be. Then he considered Little Miss's height and what size pendant would be best suited to a girl who was still very small but was not likely to remain that way indefinitely.

Eventually he sliced a section from the tip of the driftwood piece. The wood was very hard, but Andrew had a robot's physical strength, so the only question was whether the knife itself would withstand the demands he was placing on it. It did.

He contemplated the section of wood that he had separated from the bigger piece. He held it, turning it, rubbing his fingers over its surface. He closed his eyes and envisioned the way it might look if he removed a bit here, a bit there-just shaved away a little over here-and also here

Yes.

He began to work.

The job took him almost no time at all, once the preliminary planning had been carried out in his mind. Andrew's mechanical coordination was easily equal to such fastidious work and his eyesight was perfect and the wood seemed to yield readily enough to the things he wished to do with it.

By the time he was finished, though, it was much too late at night to take it to Little Miss. He put it aside and gave it no further thought until morning. Just as Little Miss was about to run outside to meet the bus that took her to school each day, Andrew produced the little carving and held it out to her. She took it from him, staring in perplexity and surprise.