In Sanskrit the word sastram has two meanings, “to command” and “to teach”. And the sastram does both, like a mother who commands when we are children and teaches when we grow up. Swamiji catogorises all our scriptural literature into seven layers. Needless to say again that the Vedas are the first and foremost. These Vedas themselves are vast consisting of over 20000 Mantras, and consist of four books, Rig, Yajur, Sama and Adharvana Vedas. As we have seen earlier, the Vedas are also called Sruti Grandhas and are the primary or moola Grandhas of our religion. Then the second layer is called Sutra literature, a literature in the form of cryptic statements or aphorisms, composed by several Rishis. Since the Vedas contained several topic strewn all over in an unorganized manner, these Sutra literature codified and clarified the same teaching, though in nutshell or capsule statements. The Sutra format makes it easy to memorise and chant. Thus we have several Sutras Gowtama Sutras, Parasura Sutras, and subject wise Dharma Sutras, Srouta Sutras etc, the most prominent one being Brahma Sutras by Vyasacharya. Then comes the third layer of literature known as Smrutis, which literally means remembered wisdom. Here also the same Vedic teaching is codified and elaborated for clarity, the important one being Bhagawath Gita itself, which contains more than 700 slokas. Thousands of verses were also written by several sages like Manu, Yagnavalkya etc. And they are beautifully organized topic wise like creation, cosmology, goals of an individual, duties of students, duties of grihasta etc all well classified. In the fourth layer we have Puranas, which is the same teaching in more expanded or magnified form. The uniqueness of Puranas is that the abstract ideas of Vedas are presented in the form of stories. For example, one single virtue “Satyam vada “ (speak truth) is narrated in Harischandra Puranam in thousands of verses. Vyasacharya himself has authored 18 Puranas and 18 Upapuranas, the most popular among them being Bhagawatham, the story of Srikrishna. Then we have Ithihasas in the fifth layer of the hierarchy. Ithihasas are basically history based lieterature and we have only two. The first one is Ramayanam written originally by Valmiki Rishi containing about 24 thousand verses. The second one is Mahabharatham, written by Vyasa, containing One lakh verses the largest literary work in the world. Here again, the aim is clarification of the Vedic teaching by personification of good virtues and bad virtues and the narration is a mixture of history and fiction. In the sixth layer we get Bhashyam literature, which is commentaries on all the above forms of literature. Adisankara alone authored Bhashyam on Gita, ten Upanishads and Brahma Sutras, without which it would have been impossible for us to understand the essence of Vedic teaching. So many Great acharyas like Ramanuja and Madhvacharya also wrote many Bhashyam. The most interesting thing is that all the commentaries attracted sub commentaries which in turn have sub sub commnentaries, and sub sub sub commentaries too. Finally in the seventh layer we have so many independent books like Vivekachudamani, Ashtavakra Gita, Hamsa Gita, Udhava Gita, Tatva Bodha, Atma Bhodha, Vedanta Dindima, Upadesa Sahasri, Sarva Vedanta Sangraha, Panchadasi and many many subsidiary books known as Prakatana Grandhas, written by several Acharyas, making it impractical to name all. Thus, the seven layers of literature put together make it impossible for anyone to master them in one lifetime. Let us pray for success in understanding tiny part of this vast ocean of knowledge. Hari om.