Born in Madrid on 19 May 1887, city where he died on 27 March 1960. Married to Dolores Moya in 1911, had three daughters and a son (Carmen, Bethlehem, Mary Elizabeth and in 1987 I Gregory Marques de Maranon “). Austere, humanist and liberal, is considered one of the brightest intellectuals of the twentieth century Spanish citation needed . Besides his scholarship, noted for his elegant literary style. Like other intellectuals of the time, became involved politically and socially: he fought against the dictatorship of Primo de Rivera and expressed critical of communism, at first supported the Second Republic but was soon criticized for its inability to unite all Spanish , to position itself increasingly to the far left. Maintained at all times from its commitment to human dignity, a critical attitude towards the excesses of both sides in the drama of the Spanish civil war, which put his life in grave danger.His contribution to medicine soon focused on endocrinology, which was one of its precursors. He created the first treaty of Internal Medicine in Spain, together with Dr. Hernando, and his book Manual of etiological diagnosis (1946) was one of the most widely used medical textbooks worldwide for its innovative approach to the study of diseases and its infinite and unpublished clinical contributions. Besides his intense dedication to medicine, wrote about almost everything: history, art, cooking, clothing, hairstyle, etc.. In their works analyzed, with a singular and unprecedented literary genre: “Bioassay”, the great human passions through historical, and psychological and physiological characteristics: the shyness in his book Amiel, resentment in Tiberius, power in The Duke of Olivares, intrigue and political treachery in Antonio Perez, one of the makers of the Spanish Black Legend, the “philandering” in Don Juan, etc..He was admitted and collaborated on five of the eight Royal Spanish Academy. While the Maranon is indelible footprint in terms of science, which makes it eternal, universal and his work even more remarkable is the discovery and “describing” the realm of ethics, moral, religious, cultural, historical … in short “human” accompanying. Nowadays, is named after the largest hospital in Madrid and numerous roads and educational institutions throughout Spain.