There are about 700 crores people in the world. If we divide total population of the world in 12 parts we arrive at figure of 60 crores. Predictions on the basis of sun signs means predicting same for 60 crores people of different age, cast, creed & religion. Where as FACT IS "TWO TWINS ARE DIFFERENT".
According to the principles of Nadi Astrology the Zodiac is divided into 12 equal sub divisions of Signs with equal subdivisions of the 27 Nakshatras. These Nakshatras are further subdivided into unequal “Sub lords”. Nadi Astrology lays greater emphasis on the sub lord which is stronger than the Nakshatra & in the same sequence the Nakshatra is stronger than the Planet.
The experience shows that the system of study of Astrology through the Sign, Nakshatra & Sub lord gives most accurate results because in this system we judge every planet on three platforms. In this system we cast the horoscope of the native by taking date, time & place of birth by drawing Lagan chart & Nirayana Bhava chalit chart. For predicting each event not a single House but combination of Houses is taken into consideration. For Timing each event Vimshottari Dasa is used with Transits.
Nadi astrology is only predictive hindu system of astrology. In traditional Hindu Astrology Parshari Astrology and Jamini Astrology are taught however these systems of astrology do not have any pin pointed method for predictions of events. Nadi Astrology deals with pin pointed predictions on all the events of life viz. Education, Litigation, Property, Vehicle Purchase, Travel, Career, Health, Marriage, Child Birth and Longevity.
How you should learn it? How you should use it? There is too much confusion surrounding Nadi Astrology now-a-days. Bhrigu Nadi, Dhruva Nadi, Sapta Rishi Nadi, Chandra Kala Nadi, Nandi Nadi etc. are the terms that you might have already heard. Some people think it as a system of astrology like Jaimini or Tajik. Some people will say that Nadi Astrology is predictions written on leafs. Others will say that Nadi astrology about thumb impression and prediction based on that. This association of Nadi Astrology with Nadi leaves and thumb impressions is more common in Southern part of India. So What exactly is Nadi astrology then?
Let me explain you in the language that you understand. This is very important for astrologers and astrology students, so listen carefully. Nadi astrology is not a system of astrology. When somebody calls it a system of astrology, he is incorrect. Nadi Astrology is a process, a batch process of writing predictions for large number of people in advance. This process of Nadi Astrology has three roles involved - A Nadi Writer, A Nadi Reader and a consultee/ client. Apart from these three roles Nadi has a techniques to for indexing those large number of horoscopes. This indexing technique is used later to find out exact note or prediction for the client. Indexing techniques of Nadi Astrology is miraculous as those can index millions of horoscopes without using software of computer. Amazing.
Coming back to the roles. Nadi Writers writes predictions of large number of people in advance and Nadi Reader reads-out those predictions for the client when client visits him. These two processes happens at different period of time. Some of the Nadis are written hundred years back and some are written couples of hundred year back. Some may be written even thousands of years back .. who knows.
Anyways, Nadi Writer writes the large number of horoscopes and predictions in advance. Different Nadis use different techniques for classification and indexing of these large number of horoscopes. Some Nadis like Agastya Nadi classifies those horoscopes based on thumb impression. Some Nadies like Chandra Kala Nadi uses Nadi Amsa for indexing and classification. Some Nadies like Bhrigu Nadi use year of birth for indexing. Some Nadis uses shadow size of the native for indexing. So various Nadis use various techniques for indexing and classification. Sometimes Nadis do also use composite techniques and combine multiple methods to search quickly.
Different Nadis also use different astrological systems for predictions. As Nadi Writers mostly writes predictions without giving much of astrology information and hence it is difficult to find out which system is being used. Different Nadis uses different systems, some are primarily transit based, some are Jaimini based, some are Parashari based and so on. For most of the Nadis, though, knowledge of system is unavailable as what is left to us is just written predictions. For example, Chandra Kala Nadi uses Parashari and Jaimini systems primarily for writing those predictions.
OK, so now you understand that Nadi is not a system but a process. A process where Nadi writers writes predictions for large number of people in advance in a indexed fashion. Nadi Writer is actually the one who knows astrology. The job of Nadi Writer ends after writing and indexing those predictions. After that job of Nadi Readers starts. When a client visit to Nadi Reader, Nadi Readers uses the indexing techniques to find out the right predictions and reads it out in front of the client. Nadi Readers is generally not an astrologer, he just reads out what is already written.
So suppose somebody says that he is using Nadi Astrology in his predictions, it is technically incorrect. He should say that I use "principles" of "Brigu Nadi" or "principles" of "Agasthya Nadi" in my predictions. There cannot be any system called Nadi Astrology unless one doesn't understand the real terminology. For example, Satya Jatakam is based on principles of Dhruva Nadi. So if you have to learn principles that Dhruva Nadi writer uses, you can go through Satya Jatakam or Jataka Satyacharya written by Sage Satyacharya.
There is a type of Nadi which doesn't use astrology at all. This is called Mantra Nadi. Mantra Nadi uses some siddhis or psychic power for predictions. These Nadis, as do not use astrology and cannot predict future very accurately. But those Nadis can predict present and past very accurately. Generally people associated with such Nadis pretend like Nadi Readers and also use Nadi leafs to look like Nadi Reader but he is actually using those low-level psychic power for predictions. One should stay away from Such Nadis.