Nadi Astrology () is a form of Hindu astrology practiced in Tamil Nadu

Tamil Nadu

Tamil Nadu is one of the 28 states of India. Its capital and largest city is Chennai. Tamil Nadu lies in the southernmost part of the Indian Peninsula and is bordered by the union territory of Pondicherry, and the states of Kerala, Karnataka, and Andhra Pradesh...

, India. It is based on the belief that the past, present and the future lives of all humans were foreseen by Hindu sages in ancient time
The texts are mainly written in Vatteluttu

Vatteluttu

Vatteluttu alphabet, also spelled Vattezhuttu alphabet is an abugida writing system originating from the Tamil people of Southern India...

, which is an ancient Tamil script. There are different schools of thought as to the author of these leaves. They were written by a Tamil sage called Agathiyar

Agastya

Agastya was a Tamil/Vedic Siddhar or sage. Agastya and his clan are also generally credited with uncovering many mantras of the Rig Veda, the earliest and most revered Hindu scripture, in the sense of first having the mantras revealed in his mind by the Supreme Brahman...

 who is said to have had divine revelations.