Don looked at them in his rearview mirror. "Amphion," he said, "stop teasing your sister."

Amphion swiveled two of his four eyes to look at Don. "She started it!" Each Dracon eye had a unique visual range: two saw to varying degrees into the ultraviolet, the third saw into the infrared, and the fourth saw into both but not in color; the combination of eyes the boys chose to bring to bear on an object not only affected what it looked like to them but also how they felt about it. They also possessed a sense that had no terrestrial analog, enabling them to detect heavy objects even when they were out of view.

Amphion and Zethus each had five limbs: three legs and two arms. If their embryonic development was a reliable echoing of their evolutionary history, the two front legs had evolved from what had been pelvic fins in an earlier aquatic form, and the thicker rear leg was derived from what had been a tail fin. The arms, meanwhile, had developed not from pectoral fins, as in humans, but rather from the complex array of bones that had supported two ancestral gills.

Dracons had only three fingers on each of their two hands, but they nonetheless came honestly by the base-ten counting system used in their radio messages. The boys each had ten feeding tendrils around their mouth slits — two pairs of them above and a row of six below; Zethus was using his tendrils just now to maneuver a hunk of cotton candy that Gillian had passed through a small airlock to him. Because their four eyes were recessed in bony sockets, Dracons couldn’t actually see their own tendrils, so whatever help they were in math involved some mental picture of their deployment, rather than actually counting them.

The original Expo 67 had been subtitled, in phrasing that seemed horribly sexist only a few years later, "Man and His World." This Expo 67 had no subtitle that Don was aware of, but "Humanity and Its Worlds" might have been appropriate: people had finally returned to the moon, and a small international colony had been established on Mars.

And, of course, there were other worlds, too, although they didn’t belong to humanity. As the timing would have it, it was now 18.8 years since Sarah Halifax had sent her final message to the stars, acknowledging receipt of the Dracon genome and explaining that her designated successor would help create Dracons here. That meant that Sarah’s pen pal on Sigma Draconis II was just now getting word that what he’d asked for was going to be done. There was, everyone assumed, a celebration of that news going on right now on that alien world; it seemed fitting to have a matching celebration here, and it would be held tonight. One could transmit signals to Sigma Draconis at any time of the day from Canada, but it seemed appropriate to beam a message into space when the stars were actually visible, although the lights from Toronto would drown out the dim sun of the boys’ ancestral home.

At the ceremony, a statue of Sarah — as she’d looked in 2009, when the first message was received — would be unveiled. After Expo 67 ended, it would be moved to its permanent home out front of the McLennan Physical Laboratories. Following the unveiling, greetings would be broadcast to Sigma Draconis not just by Amphion and Zethus — who had been sending weekly reports there for ten years now, although none of them would have been received yet — but also by dignitaries from the dozens of countries that had pavilions at the fair.

Traffic was moderate, and after an hour, the Dracmobile was getting close to their destination. Don had come back to Toronto often over the years to visit his grandchildren, and — more recently, heartbreakingly — to attend the funeral of his son Carl, who had died at the obscenely young age of seventy-two. He took this pilgrimage on each trip, but Gillian and the boys had never been this far north in the city.

As they drove along Park Home Avenue, Don was saddened to see that the library he so fondly remembered was gone. Most libraries were, of course. Don was a bit of a Luddite, and still had a pocket datacom, but Lenore and Gillian had web-accessing brainlink implants.

He drove the van into the cemetery — another anachronism — and parked it as close to Sarah’s grave as he could. The boys put their filter masks back on and they all walked the rest of the distance, kicking through fallen leaves as they did so.

Don had brought a virtual bouquet with a cold-fusion battery; the hologram of red roses would last almost forever. His kids, normally boisterous, understood he needed a quiet moment, and gave it to him. Sometimes when he came here, he found himself overwhelmed by memories: scenes from when he and Sarah were dating, events from early in their marriage, moments with Carl and Emily as children, the brouhaha when Sarah had decoded the first message. But this time all that came to mind was the celebration, almost twenty years past, of their sixtieth wedding anniversary. He’d gone down on one knee then — as he had just now to place the flowers. He still missed Sarah, every single day of his life.

He stood up and just stared for a time at the headstone, and then he read Sarah’s inscription. He turned and contemplated the blank space next to it. His own planned epitaph — "He was never left holding a Q" — wasn’t quite as nice as hers, but it would do.

After a few moments, he glanced at Lenore, wondering how she felt knowing he’d end up here, rather than next to her. Lenore, whose freckles had faded over the years, and now had fine lines on her face, must have read his mind, for she patted his arm and said, "It’s okay, hon. Nobody from my generation gets buried, anyway.

You paid for it; you might as well use it… eventually."

Eventually. In the twenty-second century, or maybe the twenty-third, or…

The age of miracle and wonder. He shook his head, and turned to face his children.

Sarah, he supposed, was nothing special to Gillian: just his father’s first wife, a woman who had died years before she’d been born and none of whose DNA she shared — not that such trivial concerns would have mattered to Sarah. Still, society didn’t have a name for such a relationship.

There was no special name for what Sarah was to the boys, either, but they would not exist without her. Amphion was staring thoughtfully at the four names on the headstone — "Sarah Donna Enright Halifax" — and must have been contemplating the same thing, for he said, "What should I call her?"

Don considered this. "Mom" wasn’t appropriate — Lenore was their mother.

"Professor Halifax" was too formal. "Mrs. Halifax" was still available; Lenore, like most women of her generation, had kept her birth name. "Sarah" conveyed an intimacy, but wasn’t quite right, either. He shrugged. "I don’t—"

"Aunt Sarah," said Lenore, who had always called her "Professor Halifax" in life. "I think you should refer to her as ‘Aunt Sarah.’"

Dracons couldn’t nod, so Amphion did the slight bow that he’d adopted to convey the same thing. "Thank you for bringing us to see Aunt Sarah," he said; one of his eyes was looking at Don, while the other three faced the headstone.

"She would have loved to have met you," Don said, and he smiled in turn at each of his three children.

"I wish I could have known her," said Zethus.

Gunter tilted his head and said, very softly, "As do I."

"She was a wonderful woman," Don said.

Gillian turned to face Lenore. "You must have known her, too, Mom — you were in the same field. What was she like?"

Lenore looked at Don, then back at their daughter. She sought an appropriate word, and, after a moment, smiling at her husband, she said, "Skytop."