Lord Siva Himself was the guru of the Saivite saint Manickavachagar. He taught Manickavachagar the ‘Namasivaya' mantra. Manickavachagar sang in praise of Siva, and his verses are moving, said T. Rajarathinam in a lecture.
Every letter in the Panchakshara mantra has significance. The letter ‘na' indicates Lord Siva's control of happenings in all the worlds. He is in charge of everything that occurs in the three worlds. The ‘ma' is a reference to the deluge, by which everything is engulfed. The ‘si' refers to the act of protection by the Lord. The letter ‘va' refers to the fact that He created all that we see in Nature. The ‘ya' shows that he created all living things. There are five aksharas in the Panchakshara mantra, and each of these five letters indicates an act of Lord Siva. The Lord is said to have five duties — creation, protection, destruction, bringing on the deluge, and showering us with mercy. These five acts of His are shown to us through the Panchakshara. Another way to look at the Panchakshara is to see each of the letters as representing the five faces of Lord Siva. Yet another meaning is to see the ‘na' as representing the earth, the ‘ma' as representing water, the ‘si' as representing fire, the ‘va' as representing the air, and the ‘ya' as representing the sky. The five letters could also be taken to indicate Siva's five colours. He is said to be golden hued, white, red, black and grey in colour.
Just as each letter in the Panchakshara has great significance, each word in the Tiruvachagam of Manickvachagar has significance. Manickavachagar uses one particular word six times. This is to indicate the six inner conflicts we have. He uses yet another word five times, to show that our five senses must go on the right path. He uses another word eight times, to show the eight qualities of Lord Siva.
He is the embodiment of gnana, mercy, joy and love. He is Omniscient. He has infinite capacity to accomplish anything. He created Nature, and is Himself Nature. He also loves Nature. That is why every temple has a sthala vriksha — a tree auspicious to that temple. That is why we also maintain gardens in temples.