Kalahasti is a holy Saivite (worshippers of Lord Siva) place in the state of Andhra Pradesh. There are five temples of Lord Siva in five different places representing the five elements, viz. fire, water, air, ether, and earth. This holy shrine represents air (vaayu). The purana (history) of this place says that a spider worshipped Kalahasthinathar, the presiding deity. The holy river Swarna Mukhi runs in this place. Atop the mountain in this holy place there is a Siva temple. In the ages gone by a hunter lived in this mountain forest. He was an ardent devotee of Lord Siva of this temple. After spending the whole day in hunting, at nights he used to visit this temple to worship Siva.
A deep desire developed in him to do pooja and abhishekha to Siva. But he did not have in his possession any pot to carry water, any basket to carry flowers or any vessel to cook food for offering to Lord Siva. So, he would place the flowers on the matted locks of his hair, carry as much as water as possible in his mouth and the meat of the animals hunted during the day in his hands. Arriving at the temple he would just spit all the water onto the Siva Linga, shake the flowers off his hair onto the Linga and offer the meat as Naivedya. At day-break he would leave the temple.
In the mornings when the priest of the temple came up to do pooja and abhishekha he found that someone had offered fresh flowers and meat for God every night. This upset him greatly. He would clean the whole place, do pooja and abhishekha and leave the temple sorrowfully. Since this strange night worship continued, the priest not knowing how to stop this , prayed intensely to Lord Shiva to give him an answer. That night the Lord appeared in his dream and instructed him to hide himself in the temple the next night and watch all that would take place. The priest hid himself in the temple and anxiously awaited the night happenings.
The hunter arrived at the temple as usual and conducted the abhishekha and pooja. Suddenly one of the eyes of the Linga started bleeding. Immediately, without a second thought, the hunter plucked out one of his own eyes with the help of his arrow and fixed it onto the Linga. He was happy to find that the bleeding stopped. However, blood started oozing out of the other eye. Immediately he decided to fix his other eye there but stopped a while wondering how he would be able to locate the right spot to fix it as with both eyes gone he would be blinded. The idea then struck him to place his foot on the bleeding eye. He plucked out his other eye and fixed it on this spot.
The priest was totally awe-struck and broke down witnessing the deep devotion of the hunter. He realized that his own devotion to the Lord was only superfluous compared to the hunter's. Just then Lord Siva appeared on the Rishaba (bull) and blessed the hunter. The priest felt a sense of fulfillment of his life being blessed with Lord Siva's darshan. The hunter was none other than Kannappa Nayanar, one of the sixty-three Nayanmars (Saivite Saints) who are worshipped by all.
Please check these: Excerpts from a discourse by our Sri Sri Muralidhara Swamiji
God gives whatever is required (by His devotee), removes whatever is not needed, leads the devotee in the path suited to him/her; Since Bhagavãn takes utmost interest in the devotee's needs the latter will not earn/attain any 'siddhi'