Koorathazhwan

Koorathazhwan, also known as Kuresa and Srivatsanka Mishra, was the chief disciple of the great Vaishnavite acharya Ramanuja. He assisted Ramanuja in all his endeavors.
Early life.
Koorathazhwan was born as Kuresan in a small hamlet 'Kooram' near Kanchi, in the year of 1010 A.D (Sowmya year, Thai month, Hastham star), in an affluent family as the son of Sri Kurattazhwar. He belonged to the clan of 'Haritha', who were popular landlords. Koorathazhwan was married at a young age to Andal, a devoted and pious lady. Both of them led a happy and peaceful life. They were deeply devoted to Lord Varadaraja Perumal. The pious couple were very famous in the holy town of Kanchi, for their unstinting philanthropy and kindness. Their children were was Parasara Bhattar and Veda Vyasa Bhattar.
Meeting Ramanuja.
Kuresan was heavily influenced by the teachings of Sri Ramanujacharya, who was staying in Kanchipuram at that time. It was the time when Ramanuja's teachings were growing popular and His fame was slowly spreading. Kuresan quickly approached Ramanuja and became his disciple. A bond was established between them and under the effective guidance of Ramanuja, Kuresan was initiated into rigorous study of Vedic scriptures and other holy works.
Meanwhile, due to other plans of the Lord, Ramanuja moved to Srirangam and the friendship between Ramanauja and Koorathazhwan came to a temporary end. Later Koorathazhwan continued his earlier philanthropic works.
Divine Plan.
Once it happened that Lord Varadaraja Perumal and His Consort Perundevi Piraati heard a heavy sound of a door being closed. The actual reason was that, Kuresan had closed the brass doors of his home, after completing his daily routine of feeding the poor.
By the order of the Lord, who appeared in the dream, the chief priest arrived at the door step of Kuresan to bring him to the Lord. On hearing this news, rather than feeling happy, Kuresan was extremely saddened, as he thought that it was a sin on his part to disturb the Lord and His Consort at the night time, by 'announcing' his charity activities.
This incident created a turmoil in the mind of Kuresan, which was a turning point in his life. At once he and his wife decided to renounce all their belongings and move to Srirangam, where Ramanuja was staying.
On reaching Srirangam, the couple were given a warm welcome and Ramanuja was very happy to have his old friend again. Kuresan became a disciple of Ramanuja and assisted him in all his works such as spiritual study, management of the temple, philosophical compositions and many others.
Soon Koorathazhwan became the hand and eye of Sri Ramanujacharya.
Journey to Kashmir.
One of the main aims of Ramanujacharya was to compose the Sri Bhasya. To compose this work, he wanted to refer Bodhayana's vritti Brahma Sutras, an ancient parchment. This work was available in the royal library of the state of Kashmir.
Ramanujacharya and Koorathazhwan, along with certain other disciples undertook the tedious journey to Kashmir and met the king of that state. The king was very much pleased with these men of divine nature and immediately granted them access to the library. But the pundits of that place were not pleased with the 'outsiders' and troubled them a lot. They put forth a condition that the 'vritti' shall not leave the library. So, Ramanujacharya and Koorathazhwan decided to read the 'vritti' within the premises of the library itself. To incur more trouble, the pundits went still further to put a condition that no notes must be taken, by reading the vritti.
Then Ramanujacharya decided to return to Srirangam and they started their journey back south. Ramanujachraya was disappointed for not making adequate reading of the vritti. But after reaching Srirangam he realized that he had lost nothing. Koorathazhwan had read the entire text of the vritti and had memorized it completely. He was able to recall the vritti, instantly and accurately word-by-word. With great sense of fulfillment, Ramanujacharya completed the Sri Bashya, which was a commentary on the Brahmasutras.
Completing "Sri Bashya" was mainly because of the involvement of Koorathazhwan. His works include "Sri Vaikunta Stavam", "Athimanushastavam", "Sundarabahustavam", "Varadarajastavam" and "Sri Stavam". These five works were collectively known as Panchastavee.
Meeting the Chola King.
After a certain period of time, the glory of Sri Ramanujacharya spread far and wide. However, as Ramanujacharya insisted people should avoid Shiva worship, the then Chola King - Rajaraja Anabaya Kulothunga chola also called as Thiru Neetru chola Boopathy - who was a practitioner of Shaivism, was offended. So, he invited Ramanuja to his "Vidvath Sadhas" to debate his philosophy. Coming to know this, Koorath alwar immediately rushed back to the mutt in Srirangam and requested Sri Ramanujacharya and the others to move away to some safer place. Though not interested in moving, Sri Ramanujacharya had to oblige to his adamant disciples. When the soldiers came to the mutt, Koorathazhwan was dressed up as Ramanujacharya. Mistaken they took him along with Sri Mahapurna (Periya Nambi) to the royal court in Gangaikonda Cholapuram. At the court ("Vidvath Sadhas") as the finale of debate ensued, the vedic scholars of Chozha king's court quoted various scriptures such as - "paraatparataram brahma tatparaat parataro hari: tatparaatparataro isha:" (Atarva veda); Srimat Haradatta Sivacharya's Vaishnava Kandanam; Basmajabala upanishad etc - to debunk Ramanuja's philosophy. As Koorathazhwar and Periya Nambi could not argue against the vedic proof, the King wrote a declaration that read "sivatparataram nasti" (meaning: "Nothing higher than Siva exists") and sent it to them. They were asked to agree and certify that declaration, or, provide vedic evidence to contest that. As they could not successfully provide the evidence, and as they did not want to accede and affix their signature either, as a desperate act of mischief, they wrote "asti dronam atha: param" (meaning: 'siva' also means a 'unit' to measure rice, in sanskrit; dronam also means another 'unit' of measure, but it's bigger than 'siva'!). [References: 1. Saiva Samaya Sarabam - Pamban Srimat Kumaragurudasa Swamigal, 2. Deivathin Kural - Kanchi Sri. Chandrasekharendra Saraswati Swamigal]
At a stage, the king got furious and ordered their eyes to be pulled out. The eyes of Mahapurna were also gorged by the soldiers and they were sent away from the court. The ripe-aged Mahapurna attained Holy Feet of the Lord (Moksha) on the way to Srirangam.
Sri Ramanujacharya meanwhile had moved to Melkote in Karnataka along with his disciples and established Vaishnavism there with the support of the local king. After the turbulence period of over 12 years had got over, Sri Ramanujacharya returned to Srirangam and the old friends reunited. Koorathazhwan lived for some more years and attained the Holy Feet of the Lord.
Thaniyan on Sri Ramanujacharya.
Koorathazhwan composed a thaniyan on Sri Ramanujacharya
 "yO nityam achyuta pAdAmbuja yugma rukma<br>
"vyAmOhatastaditarANi tRuNAya mEnE |<br>
"asmad gurOr bhagavatO asya dayaikasindhOh<br>
"rAmAnujasya charaNou SaraNam prapadyE ||" 
yO - who
nityam - always
achyuta pAdAmbuja yukma rukma vyAmOhatah - because of his excessive desire for the lotus Feet of the Lord which he considered as wealth
tat itarANi - every thing else
tRuNAya mEnE - thought as mere nothing
asmat gurOh - our AchArya
bhagavatah - having all auspicious qualities
dayA Eka sindhOh - ocean of mercy alone
asya rAmAnujasya - to such Sri rAmAnuja
charaNou - to his venerable feet
SaraNam - i take them as means
prapadyE - i prostrate
I seek the Holy Feet of Sri Ramanujacharya who considered all the worldly things and pleasures as mere nothing, because of his love towards the Divine Feet of Achyuta. He is our guru since he possesses all the auspicious qualities and therefore the ocean of mercy.