He paused, and frowned in recognition. “Darya? I didn’t know you were back.”

“Just got here. What’s happening?”

“More of the same.” And, at her blank expression, “Yesterday, he went over the physical properties of all the Builder artifacts. Today he’s supposed to present his general theory of the Builders. But yesterday he didn’t quite get through, so he’s wrapping up the rest of the artifacts this morning. I’ve got something back at my office that just has to go out today — wish it didn’t — but I’ll be around for the main event. If I can just get out of here.”

He was pulling Darya, impatient to be on his way. She held on.

“But who is he?”

“He’s Quintus Bloom. Came here from the Marglom Center on Jerome’s World, to present his new theory.”

“What’s the theory about?”

“I don’t know. No one knows. The only one who has heard it so far is Professor Merada.” Jaime pulled again, freeing his vest from Darya’s grip. “Word is out, though, that it’s something special.”

He pushed away her reaching hand, slipped past a couple standing in the entrance, and was gone.

It was no time for hesitation. Darya ducked her head and pushed her way forward, ignoring the grunts of protest and outrage. She kept her head low. It was like swimming underwater, through a sea of grey and black jackets.

Darya kept going until she saw light in front of her. She surfaced and found she had reached the front row of standing-room-only. The stage was below her and directly ahead. Professor Merada sat in an upright chair on the left side of a big holograph screen. He was looking straight at Darya, probably wondering about the disturbance created by her shoving to the front. He did not respond to her nod and little wave. By Merada’s side, spurning the use of the lectern to the right of the stage, stood a tall and skinny man dressed in a white robe.

It had to be Bloom. His forehead was flat and sloped slightly backwards, his nose was beaky, and his teeth were prominent and unnaturally white. He seemed to smile all the time, even when he was speaking. Darya studied him, and was sure that she had never seen him before. She had never heard of the Marglom Center on Jerome’s World. Yet she believed she knew every significant human worker in the field of Builder research, and every center where artifact analysis was being conducted.

“Which disposes of one more artifact,” Bloom was saying. “Elephant bites the dust. There are two hundred and seventeen more to go. You will be pleased to know, however, that we will not have to work through them, one by one, as we did yesterday. We got all the detail work out of the way then. With the taxonomy that I established, we will find that we can put all the artifacts very rapidly into one of my six overall categories. So. Let’s do it.”

The display behind him began to show artifacts, rapidly, one after another. Bloom, without seeming to look at them, offered one-sentence summaries of their salient features, and assigned each to some previously-defined group.

Darya, in spite of herself, was impressed. She knew every artifact by heart. So, apparently, did Bloom. He spoke easily, fluently, without notes. His summaries were spare and exact. The audience laughter — and there was much of it — came from wry, humorous comments that illuminated what he was saying. Darya had heard many speakers use humor as a distraction, to cover ignorance or some weak point in their argument. Not so Quintus Bloom. His wit arose naturally, spontaneously, from the text of his speech.

“Which brings us,” he said at last, “to the relief I am sure of everyone, to the end of Part One. We have finished the artifacts.”

Darya realized that she had been in the lecture hall for more than an hour. No one had moved. She glanced quickly around, and saw Hans Rebka, far off to her right. He was standing next to Glenna Omar, who wore a dazzling flaunt-it-all dress. So that’s who it had been, walking beside Hans as he vanished from sight. It certainly hadn’t taken them long to make contact. Glenna seemed able to smell any man who came from off-planet. Couldn’t Hans see her for what she was — Miss Flavor-of-the-Month?

Quintus Bloom was continuing, pulling Darya’s attention back to the stage.

“We have completed the data reduction phase. Now comes, if you will, an analysis phase. Finally we will perform the synthesis phase.”

The hologram display blinked off, and Bloom moved a little closer to the center of the stage.

“Twelve hundred and seventy-eight Builder artifacts, scattered around the spiral arm. Every one mysterious, every one ancient, and every one different.

“Let me begin by asking a question that I suspect has been asked many times before: Can we discover, in all the great variety of artifacts, any properties that seem common to all? What features do they share? They are of wildly different sizes. Their functions range from the totally comprehensible, like the Umbilical transit system between Opal and Quake in the Mandel system, to the wholly baffling and almost intangible, like the free-space entity known as Lens. They appear to be totally different. But are they?

“I suggest that their striking common property is space-time manipulation. The Builder artifacts came into existence millions of years ago, but the Builders themselves must possess an ability to work with the structure of space-time — or of space and time — as easily and flexibly as we mould clay or plastics. With that ability comes something else, something that I will discuss in a little while.”

Something else. It was a deliberate tease, inviting the audience to work out for themselves what Bloom was going to say. Darya herself had wondered many times at the apparent ease with which the Builders fabricated space-time anomalies, from the simple Winch of the Umbilical to the monstrous puzzle of the Torvil Anfract. Did Quintus Bloom believe that he had something new to say, when so many others had thought about the problem for so long? Did he even realize that the Anfract was a Builder construct? Behind the casual marshalling of facts and the easy audience command, Darya sensed a massive arrogance.

“Now I want to ask a rather different question. Within the past year, we have seen what appears to be an unprecedented number of changes to the artifacts. It is fair to ask, is this real, or is it merely something of our own imagining? Are we perhaps guilty of temporal chauvinism, believing that our own time is uniquely important, as all generations tend to think that their time is of unique importance?

“We can answer that question, thanks to the work of one of your own researchers, here at the Institute. Professor Darya Lang did the statistical analysis that shows the recent artifact changes to be unlike any recorded earlier.”

Darya felt the shock, and a rush of blood to her face at hearing her own name when she least expected it. Professor Merada was leaning forward and saying something to Quintus Bloom. White teeth flashed, and the beaky nose turned to point in Darya’s direction.

“Professor Merada informs me that Darya Lang is herself in the audience today, after being away from the Institute for a long period. I feel honored, and I hope that we will have a chance to meet after this seminar ends.

“But let me continue. We have available the statistical evidence that recent events involving the artifacts are in fact unique. But it is well known that statistics are not an explanation of anything. We have to ask and answer the question — why? Why has there been a spate of changes in the artifacts, unique in our history of them? Professor Lang’s important work, with all due respect, does not answer that question.”

The knife, sliding in hidden behind the compliment. “With all due respect” meant “with no respect at all.” Darya held her face expressionless, while people in the audience turned to look at her. Bloom went on, ignoring the reaction.