Bucke's
magnum opus was his book
Cosmic Consciousness: A Study in the Evolution of the Human Mind. The book is a compilation of various theories rather than strictly a simple record of his original mystical experience. Bucke borrowed the term "cosmic consciousness" from
Edward Carpenter, who had traveled and studied religion in the
East. Bucke's friend, Carpenter, had derived the term "cosmic consciousness" from the Eastern term "universal consciousness." In his description of his personal experience, Bucke combined his recollection with thoughts of another of his friends, Caleb Pink ("C.P.")—and others—and recorded his experience in a poetic style.
Cosmic Consciousness was a book which he researched and wrote over a period of many years. It was published in 1901 and has been reprinted several times since then. In it, Bucke describes his own experience, the experiences of contemporaries (most notably
Walt Whitman), and the experiences of historical figures, including
Jesus,
Saint Paul,
Muhammad,
Plotinus,
Dante,
Francis Bacon,
William Blake,
Buddha, and
Ramakrishna. Bucke developed a theory that posited three stages in the development of consciousness: • the simple consciousness of animals • the self-consciousness of the mass of humanity (encompassing reason, imagination, and
foresight) • cosmic consciousness — an emerging faculty which is the next stage of human development Within self-consciousness, there exist gradations among individuals in their degrees of intellectual development and talent. (Bucke considered that no doubt there would be gradations within the level of cosmic consciousness, as well.) Among the effects of humanity's natural evolutionary progression, Bucke believed he detected a long historical trend in which religious conceptions and theologies had become less and less frightening. In
Cosmic Consciousness, beginning with Part II, Bucke explains how animals developed the senses of hearing and seeing. Further development culminated in the ability to experience and enjoy music. Bucke states that, initially, only a small number of humans were able to see colors and experience music. But eventually these new abilities spread throughout the human race until only a very small number of people were unable to experience colors and music. In Part III, Bucke hypothesizes that the next stage of human development, which he calls "cosmic consciousness," is slowly beginning to appear and will eventually spread throughout all of humanity. Bucke's vision of the world was profoundly optimistic. He wrote in Part I (“First Words”) “that the universe is so built and ordered that without any peradventure all things work together for the good of each and all, that the foundation principle of the world is what we call love and that the happiness of every one is in the long run absolutely certain.” ==Involvement with poetry and literature==