“Look, it’s gone indigo, right over the mountains.” Intense saw edge of black below, purple blue above…

“That’s not indigo, it’s royal blue.”

“But they shouldn’t call it blue if it’s got some red in it.”

“Shouldn’t. Look, marine blue, Prussian blue, king’s blue, they all have red in them.”

“But that color on the horizon isn’t any of those.”

“No, you’re right. Nondescript.”

They marked it on their charts. Ls 24, m-year 91, September 2206; a new color. And so another evening passed.

Then one winter evening they were sitting on the westernmost bench, in the hour before sunset, everything still, the Hellas Sea like a plate of glass, the sky cloudless and clean, pure, transparent; and as the sun dropped everything drifted over the spectrum into the blue, until Maya looked up from her salade nicoise and clutched Sax by the arm, “Oh my God, look,” and she put her paper plate aside and they both stood instinctively, like ancient veterans hearing the national anthem from an approaching parade; Sax swallowed hamburger in a lump, “Ah,” he said, and stared. Everything was blue, sky blue, Terran sky blue, drenching everything for most of an hour, flooding their retinas and the nerve pathways in their brains, no doubt long starved for precisely that color, the home they had left forever.

Those were pleasant evenings. By day, however, things got more and more complicated. Sax gave up studying whole-body problems, sharpened his focus to the brain alone. This was like halving infinity, but still, it cut down on the papers he had to look at, and it did seem like the brain was the heart of the problem, so to speak. There were changes in the hyperaged brain, changes visible both on autopsy and during the various scans of blood flow, electrical activity, protein use, sugar use, heat, and all the rest of the indirect tests they had managed to concoct through the centuries, studying the living brain during mental activity of every kind. Observed changes in the hyperaged brain included calcification of the pineal gland, which reduced the amount of melatonin it produced; synthetic melatonin supplements were part of the longevity treatment, but of course it would be better to stop the calcification from occurring in the first place, for it probably had other effects. Then there was a clear growth in the number of neurofibrillary tangles, which were protein filament aggregates that grew between neurons, exerting physical pressure on them, perhaps the analogue of the pressure Maya reported feeling during her presque vus, who could say. Then again beta-amyloid protein accumulated in the cerebral blood vessels and in the extracellular space around nerve terminals, again impeding function. And pyramidal neurons in the frontal cortex and hippocampus accumulated calpain, which meant they were vulnerable to calcium influxes, which damaged them. And these were nondividing cells, the same age as the organism itself; damage to them was permanent, as during Sax’s stroke. He had lost a lot of his brain in that incident, he didn’t like to think of it. And the ability of the molecules in these nondividing cells to replace themselves could also be damaged, a smaller but over time equally significant loss. Autopsies of people over two hundred who had died of the quick decline regularly showed serious calcification of the pineal gland, coupled with increases in calpain levels in the hippocampus. And the hippocampus and calpain levels generally were both implicated in some of the leading current models of how the memory worked. It was an interesting connection.

But all inconclusive. And no one was going to solve the mystery by literature review alone. But the experiments that might clear things up were not practical, given the inaccessibility of the living brain. You could kill chicks and mice and rats and dogs and pigs and lemurs and chimps, you could kill individuals of every species in creation, dissect the brains of their fetuses and embryos as well, and still never find what you were looking for; for it was autopsy itself that was insufficient to the task. And the various live scans were likewise insufficient to the task, as the processes involved were either more fine-grained than the scans could perceive, or more holistic, or more combinatorial, or, probably, all three at once.

Still, some of the experiments and the resultant modeling were suggestive; calpain buildup seemed to alter brain-wave function, for instance; and this fact and others gave him ideas for further investigation. He began to read intensively in the literature on the effects of calcium-binding protein levels, on corticosteroids, on the calcium currents in the hippocampal pyramidal neurons, and on the calcification of the pineal gland. It appeared there were synergistic effects that might impact both memory and general brainwave function, indeed all bodily rhythms, including heart rhythms. “Was Michel experiencing any memory troubles?” Sax asked Maya. “Perhaps feeling that he had lost entire trains of thought — even very useful trains of thought?”

Maya shrugged. By now Michel was almost a year gone. “I can’t remember.”

It made Sax nervous. Maya seemed in retreat, her memory worse every day. Even Nadia could do nothing for her. Sax met her down on the corniche more and more frequently, it was a habit they both clearly must have enjoyed, though they never spoke of that; they simply sat, ate a kiosk meal, watched the sunset and pulled up their color charts to see if they would catch another new one. But if it weren’t for the notations they made on the charts, neither of them would have been sure whether the colors they saw were new or not. Sax himself felt that he was experiencing his blank-outs more frequently, perhaps some four to eight a day, although he couldn’t be sure. He took to keeping his AI running a sound recorder permanently, activated by voice; and rather than try to describe his complete train of thought, he just spoke a few words that he hoped would later key a fuller recollection of what he had been thinking. Thus at the end of the day he would sit down apprehensively or hopefully, and listen to what the AI had captured during the day: and mostly it was thought that he remembered thinking, but occasionally he would hear himself say, “Synthetic melatonins may be a better antioxidant than natural ones, so that there aren’t enough free radicals,” or “Viriditas is a fundamental mystery, there will never be a grand unified theory,” without having any memory of saying such things, or, often, what they might mean. But sometimes the statements were suggestive, their meanings excavatable.

And so he struggled on. As he did he saw it anew, as fresh as in his undergraduate days: the structure of science was so beautiful. It was surely one of the greatest achievements of the human spirit, a kind of stupendous parthenon of the mind, constantly a work in progress, like a symphonic epic poem of thousands of stanzas, being composed by them all in a giant ongoing collaboration. The language of the poem was mathematics, because this appeared to be the language of nature itself; there was no other way to explain the startling adherence of natural phenomena to mathematical expressions of great difficulty and subtlety. And so in this marvelous family of languages their songs explored the various manifestations of reality, in the different fields of science, and each science worked up its standard model to explain things, all constellating at some distance around the basics of particle physics, depending on what level or scale was being investigated, so that all the standard models hopefully interlocked in a coherent larger structure. These standard models were somewhat like Kuhnian paradigms but in reality (paradigms being a model of modeling) more supple and various, a dialogic process in which thousands of minds had participated over the previous hundreds of years; so that figures like Newton or Einstein or Vlad were not the isolate giants of public perception, but the tallest peaks of a great mountain range, as Newton himself had tried to make clear with his comment about standing on the shoulders of giants. In truth the work of science was a communal thing, extending back even beyond the birth of modern science, back all the way into prehistory, as Michel had insisted; a constant struggle to understand. Now of course it was highly structured, articulated beyond the ability of any single individual to fully grasp. But this was only because of the sheer quantity of it; the spectacular efflorescence of structure was not in any particular incomprehensible, one could still walk around anywhere inside the parthenon, so to speak, and thus comprehend at least the shape of the whole, and make choices as to where to study, where to learn the current surface, where to contribute. One could first learn the dialect of the language relevant to the study; which in itself could be a formidable task, as in su-perstring theory or cascading recombinant chaos; then one could survey the background literature, and hopefully find some syncretic work by someone who had worked long on the cutting edge, and was able to give a coherent account of the status of the field for outsiders; this work, disparaged by most working scientists, called the “gray literature” and considered a vacation or a lowering of oneself on the part of the synthesist, was nevertheless often of great value for someone coming in from the outside. With a general overview (though it was better to think of it as an underview, with the actual workers up there lost in the dim rafters and entablatures of the edifice), one could then move up into the journals, the peer-reviewed “white literature,” where the current work was being recorded; and one could read the abstracts, and get a sense of who was attacking what part of the problem. So public, so explicit… And for any given problem in science, the people who were actually out there on the edge making progress constituted a special group, of a few hundred at most — often with a core group of synthesists and innovators that was no more than a dozen people in all the worlds — inventing a new jargon of their dialect to convey their new insights, arguing over results, suggesting new avenues of investigation, giving each other jobs in labs, meeting at conferences specially devoted to the topic — talking to each other, in all the media there were. And there in the labs and the conference bars the work went forward, as a dialogue of people who understood the issues, and did the sheer hard work of experimentation, and of thinking about experiments.