Geoffrey Chaucer (; c. 1343 – 25 October 1400) was an English poet and author. Widely considered the greatest English poet of the Middle Ages, he is best known for The Canterbury Tales. Chaucer is known as the "Father of English literature", and he was the first writer to be buried in Poets' Corner of Westminster Abbey.Chaucer achieved fame during his lifetime as an author, philosopher, and astronomer, composing the scientific A Treatise on the Astrolabe for his 10 year-old son Lewis. He also maintained an active career in the civil service as a bureaucrat, courtier, and diplomat. Among Chaucer's many works are The Canterbury Tales, The Book of the Duchess, The House of Fame, The Legend of Good Women, and Troilus and Criseyde. His work was crucial in legitimising the literary use of the Middle English vernacular at a time when the dominant literary languages in England were French and Latin.