had earned a world-wide reputation, . . . to turn to his favorite theme of metaphysics; and now he resumed the subject of which he had never lost sight since his earliest manhood."
While engaged in his book on Stellar Evolution, and particularly while preparing an article on the Nebular Hypothesis, Dr. Croll wrote to Prof. Alexander Winchell, of Ann Arbor, for a copy of his book on World Life, which he desired to see before publishing. The new book, Stellar Evolution and its Relation to Geological Time, was published in the spring of 1889. It deals mainly with the prenebular condition of matter.
Dr. Croll was now able to dictate—not to write and hardly to read—only half an hour a day. But he had one thing to do before his life work could be completed—and he accomplished it. This was the publication of his Philosophical Basis of Evolution, a book in which he undertook to state the principle of determinism, which he declared to be the foundation stone of evolution; to examine its relation to Spencerianism and Darwinism, and to prove that "force, matter, and motion can never be determined by force, matter, and motion," reaching the conclusion that "the universe, in all its beauty, joy, and fullness of life, can never be explained in terms of matter, motion, and force; so that the whole process of evolution, natural selection included, evidently points to theism." Although it was largely of a metaphysical character, the author claimed that his main conclusions were, without exception, "deduced from facts or from fundamental principles." Dr. Croll substantially exhausted himself in finishing the manuscript of this book, and the proof sheets were revised with the help of the Rev. Dr. Caird. The publisher hurried the printing of the work, in order that the author might see a copy of it before he died. A bound copy of it was put into his hand, and he examined it with evident pleasure, observing: "My work is now done. I leave the world without a regret save one"—concern for the future support of Mrs. Croll. A few days after he had read to him the favorable review of the London Times. Two days before he died, though very weak and exhausted, he was mentally "as clear and alert as in his best days," and eager to discuss with a friend some of Mr. Herbert Spencer's views.
Dr. Croll was a man of a deeply religious nature, of the strictest orthodox belief, and of a religion the earnestness and intensity of which impressed his neighbors. His correspondence abounds in expressions marking this as one of the most essential elements of his character. His piety seems to have deepened as he grew older, and was never clearer or more emphatic than in his closing days.
