Somewhere, perhaps long ago, a man had said "I question" even as, at the same time, another had said "I condemn" and another had said "I follow". Thus far, had they travelled the same road, but here, the road was forked. One was a wide path. One an aimless twisting thing that had no destination. The other, narrow, and ever narrower as it progressed. And there would be other forks, other paths, that split and re-split as they tracked the infinite reaches of time itself....
He remembered the first thing he'd learned in his first plunge into space-mechanics research. Space cannot exist without time; time cannot exist without space. Space-time, then, is the fabric of the Universe.
So the threads were real. As real as the fact that one day in his life, he had decided to study law rather than to continue as a physicist. There had suddenly been a new split in the thread, and he chose, and had become an attorney, and then a man of politics.
What had Carl said? "... you'd've made that try for the moon a success last month instead of another near-miss ..."
And how many other might-have-beens could there be?
We conceive of Time, as it is integral with the structure of Space, an infinite ... The second thing he had learned.
And therefore—therefore each thread of might-have-been, unto itself, was.
Somewhere, there was a Congressman named Douglas Blair. Somewhere, there was an astro-physicist, an artist, a sculptor, a writer, a cab-driver, a general, a sailor, a doctor, a thief, perhaps even a corpse named Douglas Blair....
"I know," he said to the woman at his side then. "Dorothy, I think I know."
They entered the beautiful house set far back from a wide, beautiful highway on a lush, beautiful lawn.