Shiva Linga represents the whole world. It symbolizes the all-pervasive formless Shiva representing Nirguna Brahman, the attribute-less Supreme Self. He is the force behind countless forms of manifestations in our Universe.
Different types of Lingas worshipped today:
There are self-manifesting lingas known as Swayambhu-lingas that are created naturally and not through human craftsmanship. The ice-linga of Amarnath cave is an example of a natural linga formation. Narmadeswara lingas are formed from pebbles in the bed of Narmada River, in the state of Madhya Pradesh in India. They have a natural cylindrical egg shape and have smooth surface. There are 12 Jyotirlingas such as Kedarnath, Kasi, Viswanath, Somnath, Rameswaram, Mallikarjuna and so on. They represent Shiva’s manifestation as a column of light. There are five Pancha Bhuta lingas such as Kalahastiswar, Jambukeswar, Arunchaleswar, Ekambareshwar and Chidambaram. Lingas in each of these places represent one of the five elements or pancha bhuta – water, earth, air, space and fire.
Legend of Shiva Linga:
The story of origin of Shiva in Linga form is mentioned in the Puranas. Once when Vishnu was in a slumber, Brahma appeared before him in the form of light and introduced himself as the Creator of the Universe. In retort, Vishnu claimed himself to be the Architect of the Universe. An argument ensued between them to prove who is superior. During the argument, a huge column of blazing fire emerged before them. Both Vishnu and Brahma wanted to trace origin of the fire. Brahma turned himself into a swan and flew upwards, while Vishnu took the form of a boar so that he can burrow into the Earth. After long days of search they returned to the fire and offered their prayers seeking answer to their curiosity. From this column of fire, Shiva emerged with a thousand arms and legs, the Sun, the Moon and Fire as his three eyes, bearing a trident in his hand. Shiva told Vishnu and Brahma that he is the Infinite Cosmos out of which Brahma and Vishnu had originated. So, Shiva, Brahma and Vishnu are different aspects of Divinity. In Arunachaleswar temple of Tiruvannamalai, Shiva linga represents Shiva’s manifestation as the natural element of Fire.
Various interpretations of Shiva Linga:
Shiva Linga represents Brahmanda, the Cosmic egg, a shape that has no origin or end. The Narmadeswara lingas are examples of Linga representing Cosmic egg. Siva Purana mentions that Linga represents the light of Consciousness in which Prakriti and Purusha must unite for this causal world to exist. So it is also assumed to represent the union of Linga and Yoni. On one hand it signifies the forces of creation; on the other hand it is the formless Supreme Consciousness into which all creations dissolve finally.
Finally, it can be said that Shiva Linga symbolizes the primordial practice of our sages - realization of the Universe internally, that God can be awakened only through strong focus and meditation. Through the process of contemplation of our mind can we prostrate in front of Shiva, become receptive of his power and kindness and seek him by rising through different levels of consciousness.