Swami Vivekananda (Bengali: [Sami bibekanondo] ( listen); 12 January 1863 - 4 July 1902), born Narendranath Datta (Bengali: [norendronath doto]), was an Indian Hindu monk, a chief disciple of the 19th-century Indian mystic Ramakrishna.  He was a key figure in the introduction of the Indian philosophies of Vedanta and Yoga to the Western world and is credited with raising interfaith awareness, bringing Hinduism to the status of a major world religion during the late 19th century. He was a major force in the revival of Hinduism in India, and contributed to the concept of nationalism in colonial India. Vivekananda founded the Ramakrishna Math and the Ramakrishna Mission.
Back in India (1897-99)
The ship from Europe arrived in Colombo, British Ceylon (now Sri Lanka) on 15 January 1897, and Vivekananda received a warm welcome. In Colombo he gave his first public speech in the East. From there on, his journey to Calcutta was triumphant. Vivekananda travelled from Colombo to Pamban, Rameswaram, Ramnad, Madurai, Kumbakonam and Madras, delivering lectures. Common people and rajas gave him an enthusiastic reception. During his train travels, people often sat on the rails to force the train to stop so they could hear him. From Madras, he continued his journey to Calcutta and Almora. While in the West, Vivekananda spoke about India's great spiritual heritage; in India, he repeatedly addressed social issues: uplifting the people, eliminating the caste system, promoting science and industrialisation, addressing widespread poverty and ending colonial rule. These lectures, published as Lectures from Colombo to Almora, demonstrate his nationalistic fervour and spiritual ideology.  On 1 May 1897 in Calcutta, Vivekananda founded the Ramakrishna Mission for social service. Its ideals are based on Karma Yoga, and its governing body consists of the trustees of the Ramakrishna Math (which conducts religious work). Both Ramakrishna Math and Ramakrishna Mission have their headquarters at Belur Math. Vivekananda founded two other monasteries: one in Mayavati in the Himalayas (near Almora), the Advaita Ashrama and another in Madras. Two journals were founded: Prabuddha Bharata in English and Udbhodan in Bengali. That year, famine-relief work was begun by Swami Akhandananda in the Murshidabad district.  Vivekananda earlier inspired Jamshedji Tata to set up a research and educational institution when they travelled together from Yokohama to Chicago on Vivekananda's first visit to the West in 1893. Tata now asked him to head his Research Institute of Science; Vivekananda declined the offer, citing a conflict with his "spiritual interests". He visited Punjab, attempting to mediate an ideological conflict between Arya Samaj (a reformist Hindu movement) and sanatan (orthodox Hindus). After brief visits to Lahore, Delhi and Khetri, Vivekananda returned to Calcutta in January 1898. He consolidated the work of the math and trained disciples for several months. Vivekananda composed "Khandana Bhava-Bandhana", a prayer song dedicated to Ramakrishna, in 1898.

Q: Why did he go back to India
A: travelled from Colombo to Pamban, Rameswaram, Ramnad, Madurai, Kumbakonam and Madras, delivering lectures.
What is the notable lecture
repeatedly addressed social issues: uplifting the people, eliminating the caste system, promoting science and industrialisation, addressing widespread poverty and ending colonial rule. These
repeatedly addressed social issues: uplifting the people, eliminating the caste system, promoting science and industrialisation, addressing widespread poverty and ending colonial rule. These