Sages Garga, Naarada, Parasara and many others have written many treatises on Jyotisha. This shaastra was originally designed to indicate the measure of success or lack of it when vedic karmas are performed under the influence of a particular planet, star, lunar day, dark or bright fortnight etc. It was used to find out the most favorable time for the vedic karmas.
Kalpa is that what induces one to vedic action. It deals with matters such as: How should a ritual be done. What rituals should performed by men belonging to different castes and stages of life. Which rituals involve which Devata, which materials or which mantra. The kalpa shaastras have been compiled by many sages.
During the last 5000 years many veda saakhas have gone out of use due to neglect of study. Also during the rule of muslim emperors and Islamic invaders from out side many of the books were destroyed and those who maintained them were killed. Today we have only eight saakhas left with us. Rig veda has only one saakha Yajur veda has three; Saama veda have three. Atharva veda has only one saakha.
The Smritis embody the laws formulated by saints and sages. The most authoritative being the codes of Manu known as Manu Smriti. Manu according to the orthodox view was the first man. Tradition declares that the creator Brahma handed him a code of laws in one hundred thousand verses which for practical purposes he reduced to four thousand. They record civil laws, social obligations, ceremonies to be performed during birth, marriage and death. They comprise in short the daily duties, usages and customs to be observed by the castes and by people of different stages in life and their avowed purpose is to aid all men to attain the highest spiritual attainment. Among the duties and disciplines prescribed by the laws of Manu are conquest of the senses, freedom from lust and greed, study of the scriptures. One must honor old age, respect parents and injure no one. In the twelve books of Manu there is an account of creation and there are teachings regarding education, marriage, laws of the state, punishments, reincarnation, and ultimate freedom.
The two great Hindu epics The Ramayana and the Mahabharata are classified as Itihaasa. They are not included in the list of the Puranaas but honored with a separate classification. The word ‘Itihaasa' means it happened thus. Therefore, Itihaasa is a record of facts without any admixture of conjectural matters. It happened at the time it was written. Sage Valmiki wrote the Ramayana when Rama was living. Sage Veda Vyasa wrote the Mahabharata wherein he witnessed all the events connected with the lives of the Pandava princes. Itihaasa have the same importance as the Vedas. The Mahabharata is called the fifth veda.
‘Pura' means in the past. Those that narrate things of the past are called Puraanas. They however, also deal with predictions of the future. The Puraanas are the magnifying glass of