Our Understanding of the effects of sound has evolved over time. Early cultures viewed sound as sacred—something that bridged worlds, transported consciousness, or aligned people with divine forces. Healing was understood spiritually or metaphysically rather than purely physiologically. Greek philosophers (especially Pythagoras) were the first to mathematically map frequency, tuning systems, and harmonic ratios. They recognized that sound is vibration, and that vibration is measurable, an understanding that was critical for connecting sound to the physical world. "Research suggests that vibration transferred to neuronal, endothelial, and immune cells though tuning forks stimulates nitic oxide, and sets off a cascading of physiological events which directly influences our health, well-being, state of mind, and consciousness. Nitric oxide which is referred to in an abbreviated version as NO, is a very small molecule found in nature;  in the human body, it is rhythmically released into surrounding tissue as a gas and participates in the healthy function of all main organ systems.  In the body, NO creates a natural balance between the sympathetic and parasympathetic nervous systems. If the release of NO is thwarted or stopped altogether, it will lead to depressed immune function which over times results in tissue pathology.  The process begins as a lack of energy, joint pain, depression, decreased sexual drive, headaches, mild depression, memory loss, and poor digestion. Over a longer period time, if NO rhythms are not restimulated, those symptoms escalate into major diseases including cardiovascular disease, diabetes, Alzheimer's, autoimmune diseases  and cancer. Research shows that a 128 hz tuning fork will enhance the NO rhythms; the boost of NO balances the autonomic nervous system and signals a natural release of anti-bacterial, anti-virals, and free radicals on the microcellular level."  excerpt from Human Tuning, Sound Healing with Tuning Forks by Dr. John Beaulieu​​​​​​​