The Maitri Upanisad refers to the trimurti conception: Brahma, Visnu, and Shiva (IV. 5). These three forms are respectively represented as embodiments of the three gunas: rajas, sattva and tamas (V.2).
For an understanding of Shaivism, the Agamas are as important as the Upanisads. They are in form of dialogues between Shiva and his consor Uma, the bestower of all vidya (knowledge).
The Shaiva Agamas, twenty-eight in number, form the largest body of religious literature in Sanskrit. They are said to have been revealed originally by Shiva to his disciple and attendant, Nandikesvara.
The twenty-eight Shaivagamas, which are believed to have emanated from the five faces of Siva, are: Kamika, Yogaja, Cintya, Karana, Ajita, Dipta, Suksma, Sahasra, Amsumat, Suprabheda, Vijaya, Nihsvasa, Svayambhuva, Agneya, Virabhadra, Raurava, Makuta, Vimala, Candrajnana, Mukhabimba, Prodgita, Lalita, Siddha, Santana, Sarvokta, Paramesvara, Kirana, and Vatula.
The next important body of Shaiva literature is formed by the Shaiva Puranas. Of the eighteen Puranas, six are usually styled Shaiva Puranas. They are: Shiva Purana, Skanda Purana, Agni Purana, Matsya Purana, and Kurma Purana. The Shiva and Skanda are highly adored Puranas, especially the latter, which is a masterpiece of encyclopaedic interest. It contains stories about the births of Parvati, Ganesha, and and Karttikeya and the marriages of Parvati, Devakunjari, and Valli.
The Matsya Purana gives a detailed account of Siva’s destruction of Andhaka. The Linga Purana gives the philosophy of the worship of Siva in his form-cum-formless symbol, the linga.
Siva is a special favourite with Kalidasa, the great Sanskrit poet. Wherever Kalidasa mentions Shiva, he always uses glowing epithets. In this connections, we may mention Kumarasambhava where Shiva is the hero. In fact, there is hardly any book of Kalidasa where Shiva is not mentioned.
Kalidasa also alludes to different forms of Shaiva worship, anusthanas and vratas. Bharavi’s (c. sixth century) Kiratarjuniya, Ratnakara’s (ninth century) Haravijaya, and Mankha’s (c. twelfth century) Srikantha-carita also deserve mention. In Kiratarjuniya, Shiva, in the guise of a kirata (hunter), fought with Arjuna and finally blessed him with his divine weapon, the pashupata astra. The other two works depict Shiva’s heroism.
Hymns add much to the importance of Shaiva literature. One such hymn is Shiva mahima Stotra of Puspadanta written in sikharini metre.
Kashmir Saivism is an ancient system and has to its credit a very large body of literature exclusively in Sanskrit. The earliest text, Siva-Sutras, is believed to have been revealed by Siva himself to Vasugupta. The Sutra has a vrtti (gloss), a varttika (explanatory text), and a vimarsini (critical comment). The Vimarsini of Ksemaraja, the famous commentator, is held in high esteem.
Trika Saivism owes its name ‘Trika’ (triad) to the fact that it deals with Siva, Sakti, and Nara. The literature of the Trika Saivism falls into three divisions: Agamasastra, Spanda-sastr, and Pratyabhijna-sastra. The Agamas are the basic ‘revelations’, Spanda means the ‘vibration or the stir of consciousness’, while Pratyabhijna is ‘recognition’.
The Siva-drsti of Somananda is the most important Pratyabhijna work. The next important work is the Isvara-pratyabhijna or the Pratyabhijna-Sutra by Utpala, a pupil of Somananda. Commentaries on it are: Vrtti by Utpala himself, Vimarsini (laghvi vrtti) and Vivrti-vimarsini (brhati vrtti) by Abhinavagupta (eleventh century). Abhinavagupta’s Paramartha-sara is another important work. There are also commentaries from the Trika point of view on some of the Agamas like Svacchanda, Netra, Vijnana Bhairava, and Matanga. Ksemaraja’s commentary Udyota on Svacchanda Agama is an important work.
The Spanda-sastras lay down the main principles of the system. The Spanda-Sutra or the Spanda-karikas (containing fifty-two sutras) is based on the Siva-Sutra and is attributed to Vasugupta by Ksemaraja. The Spanda-Sutra and the vrtti on it by Kallata are called Spanda-sarvasva. There are, besides, four commentaries on the Spanda-Sutra, namely, Vivrti by Ramakantha, Spandapradipika by Utpala, and Spanda-sandoha and Spanda-nirnaya by Ksemaraja.
The Tantraloka in twelve books by Abhinavagupta is a monumental work and deals with Advaita Saivism comprehensively in all its aspects.
Some of the Pratyabhijna works are highly poetical thought their main concern is philosophy. For example, Utpala’s Stotravali speaks of Sakti as an expression of the joy which the Lord felt when he saw his own splendour. Sakti, emanated by delight, created herself out of herself and became the manifested world.
Saiva Siddhanta or Southern Saivism traces its origin to the Saiva Agamas. In fact, some early writers called the Saiva Agamas themselves as the Siddhanta. It treats both the Vedas and Agamas as revelations of God, the Vedas as general and the Agamas as special. While the Vedas propitiate many gods, the Saiva Agamas proclaim Shiva alone as the supreme One.
The same sentiment is echoed by Tirumular (fourth century) in his Tirumantiram in Tamil: ‘The Vedas and the Agamas are both authoritative as they emanated from God. The Vedas are general, the Agamas are specific. The learned do not discriminate’ (verse 2397).
The jnanapada of Saiva Agamas, on which Saiva Siddhanta is based, has been condensed into eight treatises called astaprakaranas: Tattva-sangraha, Tattva-nirnaya, Bhoga-karika, Moksa-karika, and Paramoksa-nirasa by Sadyojyoti Sivacarya; Tattva-prakasa by Bhoja; Ratna-traya by Srikantha; and Nada-karika by Bhatta Ramakanda.
The rituals of the Agamas are not mere kriya-kramas (methodologies), but also definite means to mystic experience. The mantras (hymns), mudras (poses and postures of fingers, hands, or body), nyasas (gestures of touching the various parts of the body for purification), etc. are highly artistic expressions of the spiritual delight that he participants, both individual and congregational, attain during worship. These procedures are written in the form of Saiva paddhatis. Composed in simple Sanskrit, these procedural texts are in use even today.
The paddhatis were all written by sivacaryas (Saiva teachers) who must have been Agamic pundits or heads of mathas.