Rabindranath Tagore FRAS ( ( listen); Bengali: [robindronath thakur]), also written Ravindranatha Thakura (7 May 1861 - 7 August 1941), sobriquet Gurudev, was a Bengali polymath who reshaped Bengali literature and music, as well as Indian art with Contextual Modernism in the late 19th and early 20th centuries. Author of Gitanjali and its "profoundly sensitive, fresh and beautiful verse", he became in 1913 the first non-European to win the Nobel Prize in Literature. Tagore's poetic songs were viewed as spiritual and mercurial; however, his "elegant prose and magical poetry" remain largely unknown outside Bengal.

In 1901 Tagore moved to Santiniketan to found an ashram with a marble-floored prayer hall--The Mandir--an experimental school, groves of trees, gardens, a library. There his wife and two of his children died. His father died in 1905. He received monthly payments as part of his inheritance and income from the Maharaja of Tripura, sales of his family's jewellery, his seaside bungalow in Puri, and a derisory 2,000 rupees in book royalties. He gained Bengali and foreign readers alike; he published Naivedya (1901) and Kheya (1906) and translated poems into free verse.  In November 1913, Tagore learned he had won that year's Nobel Prize in Literature: the Swedish Academy appreciated the idealistic--and for Westerners--accessible nature of a small body of his translated material focused on the 1912 Gitanjali: Song Offerings. He was awarded a knighthood by King George V in the 1915 Birthday Honours, but renounced it after the 1919 Jallianwala Bagh massacre.  In 1921, Tagore and agricultural economist Leonard Elmhirst set up the "Institute for Rural Reconstruction", later renamed Shriniketan or "Abode of Welfare", in Surul, a village near the ashram. With it, Tagore sought to moderate Gandhi's Swaraj protests, which he occasionally blamed for British India's perceived mental -- and thus ultimately colonial -- decline. He sought aid from donors, officials, and scholars worldwide to "free village[s] from the shackles of helplessness and ignorance" by "vitalis[ing] knowledge". In the early 1930s he targeted ambient "abnormal caste consciousness" and untouchability. He lectured against these, he penned Dalit heroes for his poems and his dramas, and he campaigned--successfully--to open Guruvayoor Temple to Dalits.

Using a quote from the above article, answer the following question: Why did he renounce it?
In the early 1930s he targeted ambient "abnormal caste consciousness" and untouchability. He lectured against these,