'Shastra' (śāstra) is a Buddhist Sanskrit term that refers to an exegetical commentary on the Dharma teachings of the Buddha Shakyamuni. It also refers to an independent treatise within Buddhism on a particular aspect of the Buddha Dharma.
The Three Explanations of Shastra
First, it is traditionally taught that shastras are recordings of interactive discussions and teachings by a Buddhist master such as Nagarjuna, Shantideva, Atisha, Tsongkapa or Hui Neng. For a Buddhist, shastras explain what is right or good and what is wrong or evil. Good is good and evil is definitely evil. One mustn't consider what is good as evil, nor should one consider what is evil as good. For a serious Buddhist practitioner such as the Sangha of Bhikshu monks and Bhikshuni nuns, religious cultivation is right and failing to cultivate the religious path is wrong.
The second topic that shastras discuss is what is deviant and what is proper. What is deviant, impure or immoral is decidedly deviant and what is proper, virtuous, pure or moral is certainly proper. A Buddhist disciple who has received the Five Precepts must not accept what is immoral and consider it to be proper, nor take what is proper and consider it to be improper. This is why there are shastra discussions between a Buddhist master and Buddhist disciples.
The third topic that shastras cover is the distinguishing between cause and effect. A cause is decidedly a cause and an effect is definitely an effect. One cannot say the a cause is an effect and that an effect is cause. For a Buddhist, the shastras teach one to make morally and philosophically correct distinctionsn and discriminations.
Shastras in Tibet
In the Buddhism of Tibet, most of the key shastras written by the famous Indian Buddhist masters were compiled into the Tripitaka collection called the Tengyur, or the "translated treatises". In the Tengyur there are more than 225 volumes of shastras.
- tenchö or bstan bcos in Tibetan implying "to protect and cure"
- Lun in Mandarin
The famous Indian Buddhist master Vasubandhu said:
- "That which subdues all the enemies, one’s own afflictions,
- And guards against future existence in the lower realms,
- Is called a ‘treatise’, because it subdues and protects,
- These two features are not found in other traditions."