Actually, now that he thought of it, losing his train of thought had been happening a lot. Or so he seemed to remember. It was an odd problem that way. But certainly he had been aware of losing trains of thought, which seemed, in their blank aftermath, to have been good thoughts. He had even tried to talk into his wristpad when such an accelerated burst of thinking began, when he felt that sense of several different strands braiding together to make something new. But the act of talking stopped the mentation. He was not a verbal thinker, it seemed; it was a matter of images, sometimes in the languages of math, sometimes in some kind of inchoate flow that he could not characterize. So talking stopped it. Or else the lost thoughts were much less impressive than they had felt; for the wrist recordings had only a few phrases, hesitant, disconnected, and most of all slow— they were nothing like the thoughts he had hoped to record, which, especially in this particular state, were just the reverse— fast, coherent, effortless— the free play of the mind. That process could not be captured; and it struck Sax forcibly how little of anyone’s thinking was ever recorded or remembered or conveyed in any way to others— the stream of one’s consciousness never shared except in thimblefuls, even by the most prolific mathematician, the most diligent diarist.

So, well; these incidents were just one of the many conditions they had to adapt to in their unnaturally prolonged old age. It was very inconvenient, even irritating. No doubt the matter ought to be investigated, although memory was a notorious quagmire for brain science. And it was somewhat like the leaky-roof problem; immediately after such a lost train of thought, with the absent shape of it still in his mind, and the emotional excitation, it almost drove him mad; but as the content of the thought was forgotten, half an hour later it did not seem much more significant than the slipping away of dreams in the minutes after waking. He had other things to worry about.

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