From Dentistry to Public Health Advocacy

Leonard Horowitz was born in 1952 and trained conventionally at first, earning a doctorate in dental medicine from Tufts University, further clinical training in periodontology and oral surgery, and a master's degree in public health from Harvard, after which he briefly taught anatomy at both universities. He moved from clinical dentistry into public health writing and advocacy in the 1990s, publishing more than two dozen books, including several that reached bestseller lists, on topics ranging from vaccine safety and the origins of infectious disease to alternative and vibrational healing.

His most consequential book for the solfeggio story is Healing Codes for the Biological Apocalypse, published in 1999 and co-authored with Joseph Puleo, which took Puleo's numerological derivation of six "solfeggio" tones from the biblical Book of Numbers and set it within a wider argument that specific sound frequencies carry restorative, even DNA-repairing power that mainstream medicine and, the book suggests, deliberate suppression have kept from wide use. The book and Horowitz's subsequent promotion of it across alternative health media made the solfeggio frequencies, and above all 528 Hz, a fixture of sound healing, meditation and New Age wellness marketing well beyond anything Puleo's original claim had proposed on its own.