Who was Sree Narayana Guru?

"1.Who was Sree Narayana Guru?

Great men are those whose lives and teachings give a new impetus to the cultural evolution of large masses of people. Their actions and messages have vital significance and universal value. Sree Narayana Guru (1856-1928) was one such superhuman who became the spiritual force behind the social renaissance of Kerala, the small state at the south-west corner of the Indian peninsula.
Romain Holland referred to the Guru as 'Jnanin of Action and a religious intellectual who had a keen living sense of the people and of social necessities.'
Rabindranath Tagore said, 'I have to frankly admit that I have never come across one who is spiritually greater than Swami Sree Narayana Guru of Malayalam.'
Sree Narayana Guru was a social and spiritual revolutionary. The slogans which he gave to his followers express his philosophy of unity in unmistaken terms.
One caste, one religion and one God for man.
Ask not, say not, think not caste.
Whatever be the religion, let man improve himself."