Ayurveda is a complete medical system, which recognizes that ultimately all intelligence and wisdom, flows from one Absolute source (Paramatman). Health manifests by the grace of the Absolute acting through the laws of Nature (Prakriti). Ayurveda assists Nature by promoting harmony between the individual and Nature by living a life of balance according to her laws.
Ayurveda describes three fundamental universal energies, which regulate all natural processes on both the macrocosmic and microcosmic levels. That is, the same energies, which produce effects in the various galaxies and star systems, are operating at the level of the human physiology--in your own physiology. These three universal energies are known as the Tridosha.