Final answer:
Thomas Carlyle, a Scottish philosopher and historian, was known as the Sage of Chelsea. This nickname refers to his status as a respected intellectual and social commentator during his time.
Step-by-step explanation:
Thomas Carlyle was known to his contemporaries as the Sage of Chelsea. He was a Scottish philosopher, satirical writer, essayist, translator, historian, mathematician, and teacher. Considered one of the most important social commentators of his time, Carlyle's works influenced various literary figures and political leaders. His home, located in Chelsea, London, where he wrote some of his most distinguished essays, became a place of pilgrimage for notable writers of the time and hence the sobriquet Sage of Chelsea.
It's notable that while Carlyle had diverse interests and made contributions to literature, his lasting renown is chiefly in the realm of history, particularly for his historical works such as 'The French Revolution: A History' and 'On Heroes, Hero-Worship, and The Heroic in History'.