According to the Siddha system, the body consists of 96 tatwangal, 72000 blood vessels and 1300 nerves. Besides these there are 10 nadis (main arteries), 10 vayu (vital pranas) and 14 veganal (natural function). The Siddha system also recognizes the role of the humoural theory (thridoshas of ayurveda namely the vatha pitha and kapha). The equilibrium of the thridoshas is called a disease. The diagnosis is done by the Siddha physician on the basis of the aforesaid thridoshas and the Ennvagai thervu (eight entities: ie. Nadi (pulse), Na (tongue), Niram (colour), Mozhi (voice), Vizhi (eyes), Todunarchi (touch), Malam (faeces) and Muthiram (urine). The treatment is mainly directed towards the restoration of equilibrium of the thridoshas.

The scientific basis of siddha medicine reinforced from the following evidences of knowledge and scientific spirit:

The understanding about the medicinal properties of herbs and minerals.

• The concept of purification of drugs
• Defining the shelf life of end products
• Preserving medicines in suitable containers

The Siddha system of medicine considers nature and man as essentially one and man is said to be the microcosm and universe is the macrocosm because what exists in the universe also exists in man. There are about 25000 manuscripts in Tamil dealing with the Siddha system. Many of them are today found in European countries. The UNESCO has currently taken them on to the wordbook of knowledge.