To this work I was especially attracted, because its preparation seemed to me to embody the highest intellectual power to which man has ever attained. The matter used to present itself to my mind somewhat in this way.... There are tens of thousands of men who could be successful in all the ordinary walks of life. Thousands who could gain wealth, hundreds who could wield empires, for one who could take up the astronomical problems with any hope of success. The men who have done it are therefore in intellect the select few of the human race, an aristocracy ranking above all others in the scale of being. The astronomical _ephemeris_ is the last practical outcome of their productive genius. In pursuing their lives men no doubt follow the line of least resistance, and Simon Newcomb here we may be sure was no exception; thus he chose to deal in his work with the heaviest and most perplexing problems with which the human intellect can engage. I do not attempt to describe or estimate what he achieved. Only a few select minds in his generation were capable of that. At his death the tributes of those who had a right to speak were unmeasured. Perhaps no human mind ever attacked more boldly the uttermost difficulties, and indeed have been more successful in the wrestle. He was set by the side of Hipparchus, of Galileo, Copernicus, Kepler, and Sir Isaac Newton. In a class thus lofty, his scientific fellows have judged that he had a title to stand. In their high strivings he was equally zealous, and his achievement was comparable with theirs. Nevertheless, had his disposition inclined him, there were many other paths into which he might have struck with success. His versatility was marked and he did try his hand at various tasks, at finance, political economy, belles-lettres. James Bryce, who knew him well, is said to have seen in him the stuff for a great man-of-affairs, a leader of armies or a captain of industry. His excursions, however, into such fields, though sometimes noteworthy in result, were transient and more or less half-hearted. His allegiance, given so early to the sublimest of pursuits, held him to the end. The Government of the United States placed him in its highest scientific position, at the head of the Naval Observatory, and his serious work from first to last was in the solemn labyrinths where the stars cross and re-cross, and here he was one of the most masterful of master-minds.