The science of medicine is of fundamental importance to man's well being and his survival, and so it must have originated with man and developed as civilization advanced. It is therefore rather pointless to try to determine the exact point of time when any system of medicine was evolved and codified.
A system of medicine is not a discovery but a gradual evolution during successive periods of history. It owes its progress to great men, who have not only enriched the science, but also society and civilization as a whole.
There are two ancient systems of medicine in India, the Siddha that flourished in the South and the Ayurveda prevalent in the North. Instead of giving the name of any one individual as the founder of either system, our ancients wisely attributed their origin to the Creator.
According to tradition, it was Shiva who unfolded the knowledge of Siddha system of medicine to his consort, Parvati, who handed it down to Nandideva and he, to Siddhars. Therefore it is called 'Saiva Sampradayam' (tradition of Shive), or 'Siddha Sampradayam'.
In the case of Ayurveda it was Brahma, the Creator of the Universe, who taught the science to Prajapati, he to Aswini Devatas and they, in their turn, to Atreya etc. So this tradition is called the Brahma or Arsha Sampradaya (the tradition of Rishis).
The inference to be drawn from these traditions is that, there is no exact point of time to which the beginning of these systems could be traced. They are eternal, without a beginning or end; they began with man .
The Tamils have a distinct civilization, which is not disputed by historians. The recorded history of the Tamils is thousands of years old. Apart from the literature of the first, the middle and the last Sangam periods which bears ample testimony to the extent of Tamil civilization and its eminence, mention is made even in contemporary Sanskrit literature about Cholas, Pandiyas and Cheras and their kingdoms.
A civilized society must naturally have had a system of medicine which catered to the health needs of its people. This was the Siddha system. The term 'Siddhi' means 'achievement' and the Siddhars were men who achieved certain results in medicine, as well as in yoga or tapas. The results in medicine were achieved by the Siddhars through their mental powers, they bequeathed to their 'Chilas' or pupils, who preserved and propagated the science.
Eighteen siddhas seem to have existed. They should have lived at different periods and bequeathed their experiences in medicine and yoga to posterity. The names of these eighteen Siddhas differ from one source to another.
It is not necessary to dogmatise which of these enumerations is correct. Some of the Siddhas, for example, Kapila and Kakabujanda have written treatises both in Tamil and in Sanskrit. It is possible that the originals were written in Tamil and that they were translated into Sanskrit later.
The following is the list of eighteen Siddhas according to one recension: 1. Nandi 2. Agasthiyar 3. Thirumular 4. Punnakkeesar 5. Pulasthiyar 6. Poonaikannar 7. Idaikadar 8. Bogar 9. Pulikai Isar 10. Karuvurar 11. Konkanavar 12. Kalangi 13. Sattainathar 14. Azhuganni 15. Agappai 16. Pambatti 17. Theraiyar and 18. Kudhambai.
Names like Bogar, Idaikadar and Theraiyar are of recent origin and these Siddhars lived probably in the middle ages. There are also authors of Siddha treatises like Sattaimuni, Yugimuni, Macha Muni, Kakabusundar etc., whose works are available in parts at the present day and are being used.
Ancient identified Medicinal plants in Tamil Nadu:
Analysis of habits of medicinal plants indicates that they are distributed across various habitats. One third are trees and an equal portion shrub and the remaining one-third herbs, grasses and climbers.
A very small proportion of the medicinal plants are lower plants like lichens, ferns algae, etc. Majority of the medicinal plant are higher flowering plants.
The State of Tamil Nadu is endowed with a very rich flora. Due to the various physiographic features and physiognomic factors, different types of vegetation exists in the state- 1. Coastal vegetation; 2. Island vegetation; 3. Vegetation of hills and mountains comprising of:
The altitude varies from sea level to 2637 m including the well known mountain ranges - the Nilgiri, the Anamalais and the Cardamom hills which harbours different types of ecological niches, ecosystem and innumerable medicinal plants.
A few ethnic tribes like the Irular, Kaanikkara, Karumpar, Palliyan, Paniyar, Sholagar, Thodar and others dwell in these ecosystems and still depend on naturally occurring or cultivated from the state (N.C. Nair & A.N Henry, Flora of Tamil Nadu, India, - Analysis - Vol. I, 1983, B.S.I., Coimbatore).
Out of this, it is found that 1474 are medicinal plants. A total number are found to be used in Siddha system of medicine which is commonly practiced throughout the state.