|Harihara, Vishnu on the left|
and Shiva on the right
The sage Shankaracharya, pilosopher of Vedanta, had come on pilgrimage to a large city in India and asked to go to the main temple to give thanks to God, but the city was inhabited mainly by people of faith Vaishnava and the temple the city was dedicated to Vishnu. This was a problem as it was known that Shankara was a Shaivite and at that time the contrasts between the two confessions were very hard.
The Brahmans of the temple therefore refused to grant permission to Shankara to enter the temple. The wise man then spoke to the Brahmans, and citizens, he explained his theory of the one God, the basis of Vedanta. To prove the correctness of his beliefs, he invited the Brahmans to go in garbhagrha, the most sacred sanctuary of the temple, one that preserves the main deity. The Brahmans went where it was kept a statue of Vishnu and found that the statue was changed. For half it was still represented Vishnu, but in the other half was represented Shiva. Harihara was born, God, half Vishnu and half Shiva, also called Shambuvishnu or Shankaranarayana.
Convinced by the words and 'miracle' of Sankara, it was allowed to enter the temple to the sage. This legend explains Harihara worship of the god half Vishnu and half Shiva, trying to end to the sectarian warfare that characterized 'medieval' Hinduism and representation of the basic concept of Hinduism throughout the oneness of God, to beyond the many forms in which it is venerated.
In Harihara, the left half represents Vishnu with his usual attributes, including the royal crown and the disk. In the half left is Shiva with matted hair, the crescent moon, the stream that represents the Ganges and the Trishula.
Hari in Sanskrit means yellow, but also fascinating, beautiful all the epithets of Vishnu and Hara means take away, remove, and is one of the 1008 names of Shiva, the destroyer, which, in fact, take away.
In Harihara then we have the preservation and destruction in one image, the space (Vishnu) and time (Shiva) present in a syncretism of the theological meaning very pregnant.
There is another tradition that harks back to the Puranas, I'll talk about in another post.