He continued his studies in England and France, before returning to Canada in 1864 to take up medical practice. In 1876 he became medical superintendent of the insane asylum in Hamilton, Ontario, and in 1878 was medical superintendent of the insane asylum in London, Ontario.

Around 1872 Bucke had what became for him a life-changing mystical experience which he called an ‘intellectual illumination.’ He spent the next thirty years seeking out other people who had a similar experience and reflecting upon the significance of such altering of consciousness. The literary result of his study, the book Cosmic Consciousness (1901), became a classic work on the subject. He theorized that a higher consciousness was a natural faculty in man at a certain state of development.

Bucke passed away after slipping on a step on February 19, 1902, in London, Ontario.