After the Parliament of Religions in 1893, in Chicago, Vivekananda spent nearly two whole years lecturing in various parts of eastern and central United States. By the spring of 1895, he was weary and in poor health, because of his continuous exertion. After suspending his lecture tour, the Swami started giving free and private classes on Vedanta and Yoga. In June 1895, for two months he conducted private lectures to a dozen of his disciples at the Thousand Island Park. Vivekananda considered this to be the happiest part of his first visit to America. He later founded the "Vedanta Society of New York”.
During his first visit to America, he traveled to England twice. His lectures were successful there. Here he met Ms. Margaret Noble, an Irish lady, who later became Sister Nivedita. During his second visit in May 1896, while living at a house in Pimlico, the Swami met Max Müller a renowned Indologist at Oxford University who wrote Ramakrishna's first biography in the West. From England, he also visited other European countries. In Germany he met Paul Deussen, another famous Indologist. He also received two academic offers, the chair of Eastern Philosophy at Harvard University and a similar position at Columbia University. He declined both, saying that, as a wandering monk, he could not settle down to work of this kind.
Swami Vivekananda's ideas were admired by several scholars and famous thinkers—William James, Josiah Royce, C. C. Everett, Dean of the Harvard School of Divinity, Robert G. Ingersoll, Nikola Tesla, Lord Kelvin, and Professor Hermann Ludwig Ferdinand von Helmholtz. From the West, he also set his Indian work in motion. Vivekananda wrote a stream of letters to India, giving advice and sending money to his followers and brother monks. His letters from the West in these days laid down the motive of his campaign for social service. He constantly tried to inspire his close disciples in India to do something big. In one such letter, he wrote to Swami Akhandananda, "Go from door to door amongst the poor and lower classes of the town of Khetri and teach them religion. Also, let them have oral lessons on geography and such other subjects. No good will come of sitting idle and having princely dishes, and saying "Ramakrishna, O Lord!"—unless you can do some good to the poor." Eventually in 1895, the periodical called Brahmavadin was started in Madras, with the money supplied by Vivekananda, for the purpose of teaching the Vedanta. Subsequenly, Vivekananda's translation of first six chapters of The Imitation of Christ was published in Brahmavadin.
Vivekananda left for India on December 16, 1896 from England with his disciples, Captain and Mrs. Sevier, and J.J. Goodwin. On the way they visited France, Italy, seeing Leonardo da Vinci's The Last Supper, and set sail for India from the Port of Naples. Later, he was followed to India by Max Müller and Sister Nivedita. Sister Nivedita devoted the rest of her life to the education of Indian women and the cause of India's independence.
Once back in India, traveled the country again, making inspirational lectures to uplift the masses, eradicate the caste system, promote the study of science, industrialization of the country, removal of poverty, and the end of the colonial rule. These lectures have been published as Lectures from Colombo to Almora and are of nationalistic fervor and spiritual ideology.His speeches had tremendous influence on the Indian leaders, including Mahatma Gandhi, Bipin Chandra Pal and Balgangadhar Tilak.
In May 1897 at Calcutta, Vivekananda founded the Ramakrishna Mission—the organization for social service. The ideals of the Ramakrishna Mission are based on Karma Yoga. Its governing body consists of the trustees of the Ramakrishna Math - the arm that carries out religious works. This was the beginning of an organized social and religious movement to help the masses through educational, cultural, medical and relief work.
Vivekananda also inspired Sir Jamshedji Tata to set up a research and educational institution when they had travelled together from Yokohama to Chicago on the Swami's first visit to the West in 1893. About this time the Swami received a letter from Tata, requesting him to head the Research Institute of Science that Tata had set up. But Vivekananda declined the offer saying that it conflicted with his spiritual interests.
Vivekananda once again left for the West in June 1899, amid his declining health. He was accompanied by Sister Nivedita and Swami Turiyananda. He spent a short time in England, and went on to America. During this visit, he founded the Vedanta societies at San Francisco and New York. He also founded "Shanti Ashrama" (peace retreat) at California, with the aid of a generous 160-acre gift from an American devotee.Later he attended the Congress of Religions, in Paris in 1900. The Paris addresses are memorable for the scholarly penetration evinced by Vivekananda related to worship of Linga and authenticity of the Gita. From Paris he paid short visits to Brittany, Vienna, Istanbul, Athens and Egypt. For the greater part of this period, he was the guest of Jules Bois, the famous thinker. He left Paris on October 24, 1900, and arrived at the Belur Math on December 9, 1900.
By this time, Swamiji’s tours, hectic lecturing engagements, private discussions and correspondence had taken their toll on his health. He was suffering from asthma, diabetes and other physical ailments. A few days prior to his demise, he was seen intently studying the almanac. Three days before his death he pointed out the spot for this cremation—the one at which a temple in his memory stands today. He had remarked to several persons that he would not live to be forty.
On the day of his death, he taught Shukla-Yajur-Veda to some pupils in the morning at Belur Math. He had a walk with Swami Premananda, a brother-disciple, and gave him instructions concerning the future of the Ramakrishna Math. Vivekananda died at ten minutes past 9 P.M. on July 4, 1902 while he was meditating. According to his disciples, this was Mahasamadhi. Afterward, his disciples recorded that they had noticed "a little blood" in the Swami's nostrils, about his mouth and in his eyes. The doctors remarked that it was due to the rupture of a blood-vessel in the brain, but they could not find the real cause of the death. According to his disciples, Brahmarandhra — the aperture in the crown of the head — must have been pierced when he attained Mahasamadhi. Vivekananda had fulfilled his own prophecy of not living to be forty years old.