Socrates was a classical Greek (Athenian) philosopher credited as one of the founders of Western philosophy, and as being the first moral philosopher, of the Western ethical tradition of thought. An enigmatic figure, he made no writings, and is known chiefly through the accounts of classical writers writing after his lifetime, particularly his students Plato and Xenophon. Other sources include the contemporaneous Antisthenes, Aristippus, and Aeschines of Sphettos. Aristophanes, a playwright, is the only source to have written during his lifetime. Plato's dialogues are among the most comprehensive accounts of Socrates to survive from antiquity, though it is unclear the degree to which Socrates himself is "hidden behind his 'best disciple'". Through his portrayal in Plato's dialogues, Socrates has become renowned for his contribution to the field of ethics, and it is this Platonic Socrates who lends his name to the concepts of Socratic irony and the Socratic method, or elenchus. The elenchus remains a commonly used tool in a wide range of discussions, and is a type of pedagogy in which a series of questions is asked not only to draw individual answers, but also to encourage fundamental insight into the issue at hand. Plato's Socrates also made important and lasting contributions to the field of epistemology, and his ideologies and approach have proven a strong foundation for much of Western philosophy that has followed.

Swami Vivekananda 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. He is perhaps best known for his speech which began, "Sisters and brothers of America ...," in which he introduced Hinduism at the Parliament of the World's Religions in Chicago in 1893. Born into an aristocratic Bengali Kayastha family of Calcutta, Vivekananda was inclined towards spirituality. He was influenced by his guru, Ramakrishna, from whom he learnt that all living beings were an embodiment of the divine self; therefore, service to God could be rendered by service to mankind. After Ramakrishna's death, Vivekananda toured the Indian subcontinent extensively and acquired first-hand knowledge of the conditions prevailing in British India. He later travelled to the United States, representing India at the 1893 Parliament of the World's Religions. Vivekananda conducted hundreds of public and private lectures and classes, disseminating tenets of Hindu philosophy in the United States, England and Europe. In India, Vivekananda is regarded as a patriotic saint and his birthday is celebrated there as National Youth Day.

Sri Aurobindo was an Indian philosopher, yogi, guru, poet, and nationalist. He joined the Indian movement for independence from British rule, for a while was one of its influential leaders and then became a spiritual reformer, introducing his visions on human progress and spiritual evolution. Aurobindo studied for the Indian Civil Service at King's College, Cambridge, England. After returning to India he took up various civil service works under the maharaja of the princely state of Baroda and became increasingly involved in nationalist politics and the nascent revolutionary movement in Bengal. He was arrested in the aftermath of a number of bomb outrages linked to his organisation, but in a highly public trial where he faced charges of treason, Aurobindo could only be convicted and imprisoned for writing articles against British rule in India. He was released when no evidence could be provided, following the murder of a prosecution-witness during the trial. During his stay in the jail he had mystical and spiritual experiences, after which he moved to Pondicherry, leaving politics for spiritual work.