This section is from the book "Some Contributions Of South India To Indian Culture", by S. Krishnaswami Aiyangar. Also available from Amazon: Some Contributions of South India to Indian Culture.
In the cult of bhakti the first feature to be taken note of is, unalloyed affection for God, and this affection springs from the notion that God looks after man with an affectionate interest superior even to that of himself, and therefore deserves the return of unqualified devotion.1
Such an affection when it does exist exhibits itself on all occasions whenever there should be the slightest stimulus as in the case of Kannapa at the mere mention of the name God, and afterwards at sight of Him. Unless devotion is exhibited to the fullest extent of singlehearted-ness it is hardly possible to expect Him to exhibit His grace to the suffering human beings. According to Appar it is impossible that God should exhibit himself unless one performs his devotion with a mind unalloyed with other feelings than that of affection and devotion. A similar idea is more forcibly expressed in the Tirumandiram of Tirumular. The offering of sacrifice of one's own flesh by cutting it from out. of one's own body and throwing it into a fire lighted with one's own bones is not as efficacious to evoke His grace readily as devotion which melts away one's heart and mind.
1 Compare Appar.
This goes one step further when the notion gets to prevail that pilgrimage to holy places, the contemplation upon the supreme and the performance of prayer on the approved style are all of them of no use in comparison to the realising of oneself in the extremity of affection for God himself.
This extraordinary affection for God springs in a human being as a result of deeds in previous existences without regard to fruit thereof and as the result of Siva's grace and that grace alone.
In the last resort the moment that one attains to this single-minded and unalloyed devotion, he attains to the condition of Siva, as this affection for him is not separate from Siva himself. Where this affection exists there Siva is bound down to the offer of this devotion. Wherever there is this affection, there Siva becomes visible.
The story of Kannappa is intended to illustrate this development in the course of Siva bhakti. The extraordinary devotion that the uncultivated hunter exhibited is believed to be due to what he did in his previous incarnation as Arjuna with whom Siva wrestled in the disguise of a hunter. It is the ripened effect of his good deeds that required merely the stimulus of the mention of the name of Siva to make him lose control over himself altogether like a virtuous young wife whose affection overpowers her completely at the mention of the name of her beloved. Being an uncultivated rude man not knowing how exactly to exhibit his devotion at sight of God he could only show his affection in the manner he was accustomed to do, and exhibited it as a father or mother would at the sight of a long lost child. But the devotion that he felt for Siva so overpowered him that he forgot altogether the animal requirements such as hunger, sleep, etc., for six days.
In regard to his performance of devotion, that is the result of the ignorance that goes along with the birth and bringing up of this hunter. What is acceptable to Siva and what is not, requires a preceptor to teach. Such a preceptor he had not had. And having heard but imperfectly what another man has been doing by way of devotion, he just imitated, to the very best of his ability, what he thought was being done by that other person, who, he thought, ought to know. So he bathed the linga, cleaned the surroundings and provided the food in a manner that appealed to him. In spite of all this there was at the back of it all in the rude crude man a devotion which knew no limit and which shrank from nothing by way of sacrifice to do that which according to him pleased Siva. It is this singleness of purpose in devotion that made even the objectionable form of worship acceptable to Siva and this same idea is expressed in the Tiruvasakam of Manikkavasakar.
The crisis of this devotion is reached in regard to Karmappa when it comes to Siva's bleeding eye. The hunter had absolutely no hesitation in pulling out his own eye to put in place of the ailing eye of Siva as he thought, and when that is done, the ultimate limit of devotion is reached. Karmappa is ripe for the attainment of Sivahood and attained it as a result of the grace of Siva which showed itself by look.
Thus then we see from the history of this devotee that bhakti as understood by the early Saivas was not incompatible with other forms of propitiation of God, but gradually developed by adding on the teacher to make bhakti exclusively the method for the attainment of God's favour.
It was already pointed out that in its undeveloped form bhakti consisted merely in the exhibition of unalloyed affection for God by some form of service however simple or humble. Visiting places of holy reputation, or doing some act of personal or even menial service to God in some temple or elsewhere, was apparently considered enough provided the feeling within of unmixed devotion was swelling up as occasion afforded; and where persons subject to this ebullition of emotion had the means to give vent to this feeling, there naturally came the outpouring of the heart in the shape of verses in prayer. The works of such Saiva devotees as left their impress upon their contemporaries were collected some time after and put in form for being chanted, and constituted the canonical literature of the Saivas in Tamil. These were naturally thrown in forms peculiar to the expression of the feelings evoked, and the very composition of these poems partook of the character of the modes of expression peculiar to Tamil literature, and defined by Tamil grammarians and rhetoricians. This peculiar method of exhibition of one's love to that particular form of God which appealed to his heart, gave the whole body of this literature a peculiarity all its own. These poems were in course of time set to music and were adapted to representation by the art of dancing. A class of people set up separately for the study and development of these features of the works, so that one set came to be known as specially expert in setting the tune and rendering the poems in music, and the other, generally, women, gave themselves up to the practice of the art of rendering it by dancing to the accompaniment of music. It is these developments that made the greatest appeal, and maintained the character of the melting strains of music, to the songs of these devotees, even to the present day. Practised within limits and under the control of the dominating passion of selfless devotion to God, it exercises an influence unique in character. But at the same time it is liable to abuse where the controlling feeling is feeble, and when pretenders set up for prophets. This feature of the devotional works seems to have attained full development at the time when the works were originally collected and put in form about the tenth century A. D. Though the Vaishnava devotional works partake of this character to a great extent they did not combine the practice of the accessory arts in connection therewith in the same form as Saiva devotional works. This special development seems to be what ultimately associated bhakti with the Tamil country peculiarly in works treating specially of the subject.
One other feature seems also to come into prominence in the course of development of this school. This feature is the emergence of the saving priest or preceptor who becomes essential to the attainment of salvation; and unless one attains to what is called diksa from a guru or preceptor of the proper kind Siva's grace becomes impossible. As far as it is possible to trace this institution, we see that the preceptor does not figure prominently in the case of the early and less developed devotees, but with the later ones the preceptor becomes indispensable; and this feature of the preceptor has developed a prominence, which it has not since lost, in regard to Manikkavasakar in whose case the preceptor proves an indispensable necessity. This feature attained to its own peculiar development and gave rise ultimately to the development of the sects as we shall see.