One morning he said:  “I was awake a good deal in the night, and I tried to think of interesting things.  I got to working out geological periods, trying to think of some way to comprehend them, and then astronomical periods.  Of course it’s impossible, but I thought of a plan that seemed to mean something to me.  I remembered that Neptune is two billion eight hundred million miles away.  That, of course, is incomprehensible, but then there is the nearest fixed star with its twenty-five trillion miles —­twenty-five trillion—­or nearly a thousand times as far, and then I took this book and counted the lines on a page and I found that there was an average of thirty-two lines to the page and two hundred and forty pages, and I figured out that, counting the distance to Neptune as one line, there were still not enough lines in the book by nearly two thousand to reach the nearest fixed star, and somehow that gave me a sort of dim idea of the vastness of the distance and kind of a journey into space.”

Later I figured out another method of comprehending a little of that great distance by estimating the existence of the human race at thirty thousand years (Lord Kelvin’s figures) and the average generation to have been thirty-three years with a world population of 1,500,000,000 souls.  I assumed the nearest fixed star to be the first station in Paradise and the first soul to have started thirty thousand years ago.  Traveling at the rate of about thirty miles a second, it would just now be arriving in Alpha Centauri with all the rest of that buried multitude stringing out behind at an average distance of twenty miles apart.

Few things gave him more pleasure than the contemplation of such figures as these.  We made occasional business trips to New York, and during one of them visited the Museum of Natural History to look at the brontosaur and the meteorites and the astronomical model in the entrance hall.  To him these were the most fascinating things in the world.  He contemplated the meteorites and the brontosaur, and lost himself in strange and marvelous imaginings concerning the far reaches of time and space whence they had come down to us.

Mark Twain lived curiously apart from the actualities of life.  Dwelling mainly among his philosophies and speculations, he observed vaguely, or minutely, what went on about him; but in either case the fact took a place, not in the actual world, but in a world within his consciousness, or subconsciousness, a place where facts were likely to assume new and altogether different relations from those they had borne in the physical occurrence.  It not infrequently happened, therefore, when he recounted some incident, even the most recent, that history took on fresh and startling forms.  More than once I have known him to relate an occurrence of the day before with a reality of circumstance that carried absolute conviction, when the details themselves were precisely reversed.  If his attention were called to the discrepancy, his face would take on a blank look, as of one suddenly aroused from dreamland, to be followed by an almost childish interest in your revelation and ready acknowledgment of his mistake.  I do not think such mistakes humiliated him; but they often surprised and, I think, amused him.