The Goddess once playfully closed the eyes of her Beloved thereby plunging the world into darkness and causing suffering to all living beings. The Universal mother comprehending her folly started worshipping Lord Siva in the form of a Lingam to absolve herself of the sin and reunite with him. After first visiting Kanchipuram, Parvati proceeded to Tiruvannamalai to do her penance. While performing penance at Pavalakundru (with the help of Sage Gautama), the demon Mahishasura came and disturbed Parvati’s tapas. The Mother then took the form of Durga Devi and destroyed the demon on Full Moon Day of the Tamil Month of Karthigai during the auspicious period of Pradosham. Satisfied with his Goddess, Lord Siva presented himself in the form of Fire atop the hill and merged with Parvati - thus was created the half-man, half-woman aspect of the Lord, symbolising the oneness of all beings. To commemorate this event, every year during the festival of Annamalai Deepam, Lord Ardhanarishvara presents himself as Jyoti Swarupa to his devotees.
           This fusion of Siva and Shakti representing the male and female halves, transcends the distinction and limitation of male and female and takes the Lord to a level beyond gender-manifest Brahman, realization of which means liberation. Siva is snow-white while Shakti is golden. He is substance while She is substrate. Siva is static; Shakti dynamic and creative. Siva is Being and Shakti is Becoming. He is One; She is many; He is Infinite and She renders the Infinite into finite; He is formless and She renders the Formless into myriad forms; But both are one. Siva and Shakti exist in Nirmala Turiya state (Stainless Purity).

When it comes to worship of Ardhanarishvara, some worship the Siva aspect and some worship the Shakti aspect. Siva is viewed as the Holder of Power, though he is inert. Siva is shava (dead body) without shakti. All the power in creation, maintenance, and dissolution rests with shakti. But the Great Mother does not exist without Siva. When they become one Ardhanarishvara becomes a being of generative and constructive force.
           Philosophically, this form portrays the boundless Grace of God. The formless God is called Parashiva. On Its own free-will for the benefit of pashus (souls), which are drowned in pasha (bondage), It thinks to create the worlds. Its dynamism of creation thus springs out of It, which is called Shakti. Now Shiva and Its power Shakti create everything. This is the form of their togetherness that makes every existence active. Siva and Shakti are one and the same Supreme. They are associated like the person and the action of the person. They are one and the same like ice and the water - one becomes the other. Shiva and Shakti are compared to gold and gold ornaments; they are the same; Shiva is hypostasis and when this force fuses with Shakti, it results in a multitude of manifestations.

[A. Venkatraman]