If genius is the capacity for taking infinite pains, Percival Lowell possessed it abundantly from his study of Esoteric Shinto, in his earlier life in Japan, to his great calculation of the position and orbit of an unknown planet beyond Neptune, at the close of his life. In determining facts he was thoroughly and rigidly scientific, leaving nothing unexplored that bore upon the subject; and in his astronomical investigations it became clear to him that better methods of doing it were required. At the outset, therefore, he set up his Observatory in an atmosphere steadier than that where the older telescopes, and almost all of those then in existence, did their work; thus seeing much not visible elsewhere.

But in addition to industry he had an inflammable intellect, easily ignited by any suggestion or observation, and when alight glowing in intensity until the work was done. He had also a highly vivid imagination, compared with many men of science who proceeded more cautiously; and hence he sought, not only to ascertain new facts, but to draw conclusions from them more freely than is customary with experts of that type. This he felt had often been true of those who made advances in scientific thought, and he regarded himself as standing for a time somewhat apart from most men in his own field. Such an attitude, and the fact that he had taken up observational astronomy in middle life, unconnected with any other scientific institution, tended to make many professional astronomers look upon him askance. So he plowed his own furrow largely by himself in the spirit of a pioneer, and this little volume is an attempt to tell what he accomplished.

The writer is very grateful to the Houghton, Mifflin Company, the Macmillan Company, The Atlantic Monthly, Rhodora, the Scientific American, and Miss Katharine G. Macartney (on behalf of Mrs. George Gould) for permission to quote, sometimes at great length, from books and articles by and about Percival. The writer desires also to express his deep obligation to Mr. George R. Agassiz, his brother’s intimate friend and helper, to Dr. Vesto Melvin Slipher, Dr. Carl O. Lampland and Mr. E. C. Slipher of the Lowell Observatory at Flagstaff, for reading the manuscript and giving advice; and to Professor Henry Norris Russell of Princeton University, for his kindness in not only doing this, but for writing the two appendices that follow this volume. Without their help the astronomical part of this book would have been sadly defective. They have pointed out advances in knowledge that have made certain of Percival’s opinions, particularly earlier ones, no longer tenable. Some of these he changed during his lifetime, others he would have changed had he lived to see the more ample facts since known. Nor is this a criticism of his work, for astronomy has been advancing rapidly of late; and when that is true no man can expect all his views, even if accepted at the time, to endure. Change in opinions is the penalty of growing knowledge. It is enough that a man has helped to push knowledge and thought forward while he lived, and this Percival, with the exhaustless energy of his nature, certainly did.

Boston, October 21, 1935.