Dr. Henry Clay Allen was one of the guiding lights of Hahnemannian homeopathy. Even though he was steadfast in his adherence to the principles of Hahnemann, he always strived for constructive discussion. After receiving his graduation homeopathic training at Cleveland Homeopathic College at Cleveland, Ohio in 1861, he moved to Detroit and was appointed Professor of Materia Medica at the University of Michigan, Ann Arbor in 1880.

In 1892 Allen helped found the Hering Medical College and hospital and worked there as Dean and Professor of Materia Medica until his death. During his tenure, he was respected and loved as few men are during their lives.Besides writing many articles in this and other homeopathic journals he wrote numerous books. Some of Henry Allen's well-known works include: Keynotes of the Materia Medica with Nosodes, The Materia Medica of the Nosodes, The Homeopathic Therapeutics of Intermittent Fever, The Homeopathic Therapeutics of Fever, Therapeutics of Tuberculous Affections