He was a keen student of mental pathology, and for some time before his death was reckoned among the leading alienists of the continent. Certain interesting and suggestive studies of the relation which appears to exist between the so-called sympathetic nervous system and the moral and emotional nature, but especially his _magnum opus_, _Cosmic Consciousness_, published the year before his death (1901), reveal the direction of his dominant interest. From 1877, he was one of Whitman's closest friends, and became subsequently his principal biographer.[586] In the printed recollections of his first interview with Whitman,[587] Dr. Bucke recalls the exaltation of his mind produced by it; describing it as a "sort of spiritual intoxication," which remained with him for months, transfiguring his new friend into more than mortal stature. It is another instance of the almost incredible power of the invalid's personality. [Illustration: RICHARD MAURICE BUCKE] * * * * * Whitman's own jottings and records of the period testify to his increasing physical vigour. He goes, for instance, to the Walnut Street Theatre, to a performance of Joaquin Miller's _The Danites_, accompanied by his friend the author.[588] In the summer of 1878, and in the succeeding year, he is again a guest both of John Burroughs and of J. H. Johnston.[589] On the second occasion, he had delivered his lecture on the "Death of Lincoln" in the Steck Hall, New York; promising himself anew, that if health permitted, he would even now set forth on the lecture tour which he had so long contemplated.[590] But though, in the autumn, he made, with several friends, an extended tour of some sixteen weeks beyond the Mississippi, he did not accomplish this cherished scheme. * * * * * At night on the 10th of September, Whitman and his party left Philadelphia, westward bound. Walt delighted in the magic speed and comfort of the Pullman;[591] in which, lying awake among the sleepers, he was whirled all through the first night up the broad pastoral valley of the Susquehanna, curving with its thousand reedy aits about thick-wooded steeps; and on, over ridge and ridge of the Alleghanies, till morning found them at smoking Pittsburg. Crossing the Ohio, almost at the point whence he had descended it thirty years before on that fateful southern journey, the good engine, the Baldwin, hurried them all that day through rich and populous Ohio and Indiana. Whitman was not disinclined to acknowledge a personality in the fierce and beautiful locomotive which he had already celebrated in a poem full of fire and of the modern spirit.[592]