The Agam are of three kinds. The Shiv-Agama, the Shakty-Agam and the Vaishnav-Agam according to as they treat of the Deity Shiv, Shakti and Vishnu as the object of worship. The Agam are also called Tantra and there is practically no difference between the two names specially between the Agam of the Shiv and Shakti schools, both of them are believed to have been delivered by Shiv to his consort - Paarvatee. Generally the Shaiv-Agam are called Agam and Shakty-Agam are called Tantra. Yet Shaiv-Agam have an independent status and their origin is as old as three thousand years. The Shiv-Agam are 28 in number. But all of them are not available, only few of them are available. Besides 28 principal Shiv-Agam, there are many secondary Agam which intend to explain the subject matter of the principal Agam.

In connection with the Agam, two important questions arise - the age of the Agam and the contents of the Agam. As regards the first question, the age of the Agam can well be determined from the reference made to them in various works. Harit, a writer of Smriti and Kaalidaas the world famous Sanskrit poet refer to the Shiv-Agam and both of them lived in the first century of the Christian era. Various Puraan namely Skand Puraan, Soot Sanhitaa, Brahm Geetaa and Shiv Puraan mention the Agam. In Koorm Puraan a reference is made to the fact that Shree Krishn was taught Aagamik Philosophy by Upamanyu. In the Shaanti Parv and Dron Parv of Mahaabhaarat, reference has been made to the Shiv-Agam. In Maitraayan Upanishad, Aagamik literature is referred to twice. The Shwetaashwet Upanishad is certainly an Aagamik Upanishad later followed by other Aagamik Upanishad, like Atharva Shiraas and Kaivalya. From all this foregoing account it can well be concluded that the Agam have their origin in times almost coeval with the Aaranyak.

The Aaranyak which form part and parcel of the Ved and the Agam confront each other as two independent modes of thought. This fact is brought into bold belief, when we take into consideration the contents of the Vaidik religion and the contents of the Aagamik religion.

(1) The Vaidik religion consists in the performance of sacrifices with all rites and rituals, while the Aagamik religion consists in the worship of the deity - Shiv, Shakti and Vishnu.

(2) The Vaidik deities were the forms of nature and the Vaidik religion was a system of propitiation of those nature powers. Powers by means of sacrifice offered into fire regarded as the mouth of the Deities; while Aagamik deity was personal Deity that controlled the forces of nature.

(3) The oblations in the case of Vaidik worship were consumed by the Deities through their mouth, the fire; while the Aagamik Deities took only the subtle portion of the offerings exhibited to them as Prasaad or
consecrated food.

(4) The Vaidik religion was polytheistic and the different Deities were invoked for different purposes because each Vaidik Deity has a different function in the scheme of the Universe; while the Aagamik religion being monotheistic only one Deity was worshipped, that had all the functions of the Universe in his or her hands.

(5) The Ved consist of the Mantras addressed to the different Deities and recited during the performance of the sacrifices in honor of those Deities; while the Agam contain prayers consisting of various names of
the Deity and salutations addressed to the Deity.

(6) The Vaidik worship consisted of the offering made to gods, while the Aagamik worship was personal service rendered to the God, like washing, decking and feeding them.

(7) The Vaidik gods being the forces of the nature had no physical representation, while the Aagamik Deities were represented by means of a visible emblem or image.

(8) There is no trace in the hymns of the temple worship, while the worship of the idols in temples is purely Aagamik. The Vaidik religion is the fire cult while Aagamik religion is the Deitic cult.

(9) The Ved kept the door of religion restricted to some people while the Agam kept the door of religion open to all without any distinction.

(10) The Agam treat the Yog Philosophy and Yaugik practices which are all together absent in the Sanhitaa or Vaidik hymns.

The Kriyaa-pad represents the Satputra Maarg, the path of the son serving the will of his father. It is the higher step of worshipping God under the mental image. In this stage the rites are indicative of purification of the mind and heart. The worshipper behaves towards God as a son does towards his father with a combination of purity and piety. Yog-pad represents Saha-Maarg which indicates the spirit of an associate. Here the worshipper behaves towards God as an associate. The whole spirit of the worshipper is being affiliated to God through the practice of Yog or meditation. Gyaan-pad represents Sanmaarg which means the attainment of Saayujya or atonement with God. In this condition the subject and the object become indistinguishable and the worshipper becomes possessed of Samaadhi or trance. In the Sahamaarg, the worshipper starts with the idea of being similar to God and attains similarity which by the Sanmaarg expands into Saayujya or atonement.

The main three Aagamik Schools, Shiv, Shakti and Vaishnav maintain three ultimate realities, namely
(1) A supreme being with male or female aspect predominant.
(2) The group of individual souls.
(3) The objective universe as real.

These three realities are given different names in the three different schools.

All the three schools agree in opposing and demolishing the Maayaavaad or the illusion theory of the Vedaant. Thus says Pauskar-agam: "If the world is an illusion of the conscious being the effected world will be a hollow reality. How can the world which is established to be really existing by all methods of proofs be a false transaction of consciousness? "

The Agam do not regard the world as a false show. The Universe is real because, as there is absolutely no difference between Brahm and the Universe, just as there is no difference between a pot and clay of which it is made, the reality of the universe necessarily follows from the reality of Brahm. Intense devotion or sincere Bhakti to deity forms another common feature of the three Aagamik Schools. The movement of Aagamik devotion gave rise to the art of temple building and the making of the images which in India, in South India especially, has reached a higher order of perfection. It also gave rise to devotional lyric poetry full of poetic imagery. So also music, singing and dancing developed fast under the influence of the Agam.

Dr. Radhakrishnan in his "Outlines of Indian Philosophy" has observed thus:
"This living Hindu religion of today from Cape Comorin to the remotest corners of Tibet is essentially Taantrik. Even the genuine Vedic rites that are preserved and are supposed to be derived straight from the Ved, namely the Sandhyaa, have been modified by the addition of Taantrik practice."

The two streams of thought, the Aagamik and the Vaidik, gradually gravitated towards each other. After running side by side for long time they acted and reacted on each other and modified each other's practice in religion. Attempts were later made to reconcile the differences between them and to establish the unity of thought in Hinduism.

Historically considered Veer Shaivism is a fine and full blown flower of Shaivism. For Shaivism as well as for Veer Shaivism the 28 Shiv Agam are the scriptures. But Veer Shaivism considers the latter two parts of the Agam as scriptural authority. Since the end portion of the Agam is regarded as authority Veer Shaivism is known as Agamaant. Shiv is the worshipping deity for Shaivism and Veer Shaivism in the form of Ling. The Shaiv worship Shiv Ling in the temples while the Veer Shaiv wear the miniature form of Shiv Ling known as Isht Ling. The Ling worn on the body is made of light grey slate stone and to be kept intact all through the wearer's life, it is coated all over with the fine durable black paste prepared out of certain ingredient. The coating is called Kaanti or covering. The Ling is worshipped by placing it on the palm of the left hand. This is the subjective mode of worship in which the devotee and the Divine are facing each other.

The lowermost Chakra is the basis plexus called Moolaadhaar. It has four branches or petals and the shape of a triangle. The second Chakra is Swaadhishthaan which is situated in the pelvic region and it has six petals. The third Chakra is the Solar plexus with ten petals and its location is in the region of the navel. The fourth Chakra is the Anahat which has twelve petals and is located in the region of the heart. The fifth Chakra is Vishuddhi situated in the region of the throat and it has sixteen petals. The sixth is Aagyaa Chakra which has two petals and is situated between eyebrows. This is called Plexus of command.

In the process of Yog, the centers have a fixed physiological use and a general function. The Moolaadhaar governs the physical down to the subconscient. The abdominal center the Swaadhishthaan governs the lower vital. According to Veer Shaivism, these two Chakra represent the domain of Isht Ling and are respectively occupied by the sub-forms of Isht Ling -- Aachaar Ling in the Moolaadhaar and Guru Ling in Swaadhishthaan Chakra. This is the place of Tyaagaang. The navel centre or Manipur governs the larger vital and the heart centre or Anahat governs the emotional being. These two form the vital or the intermediate plane. According to Veer Shaivism this is the plane of Bhogaang and is the domain of Praan Ling or the vital because the vital force of consciousness functions here. The throat centre or Vishuddhi Chakra governs the expressive mind, here consciousness assume concrete form of the sound. The center between the two eyebrows governs the will. According to Veer Shaivism this is the plane of Bhaav Ling - the higher intellectual plane.

The human body is identified with Tyaagaang with Isht Ling working behind it. The autonomous nervous system with Bhogaang with Praan Ling working behind it; the central nervous system or cerebrum with Yogaangwith Bhaav Ling working behind it. The bodily mechanism is Tyaagaang because it is to be directed towards the higher and in performance to the demands of matter. Here the Isht Ling aids the soul when it becomes conscious of the higher end. Full faith in the Divinity in the spirit of submission is the means to that end. The faith in relation to Shakti or the devotee is Shraddhaa which develops into Nishthaa or singleness of purpose of Mahesh. In the first stage Aachaar Ling, the practical and in the second stage Guru Ling, the perceptive are aroused for giving the soul and an insight into the spiritual truth. This is the first process of sublimation in the upward march of the soul. Here the soul is purified and divested of the thoughts of the worldly life. Aachaar Ling and Guru Ling are connected with Aadhaar Chakra and Swaadhishthaan Chakra with the corresponding awakening of the powers in them.