Eugenio Colorni (1909–1944) was born in Milan to a well-to-do Jewish family steeped in the tradition of the Risorgimento. A philosopher and a student of G. A. Borgese (aesthetics) and P. Martinetti (metaphysics), he graduated in 1930 with a thesis on Leibnizian individualism supervised by Martinetti.

To continue his studies, he took up residence at Berlin and Marburg as a Reader of Italian. During this time, he had his first meeting with Ursula and Albert Hirschmann. In 1933, he completed his specialisation in Milan with a thesis on the early philosophy of Leibniz, and became a high-school professor of philosophy.

He then moved to Trieste where he joined the ‘Centro Interno Socialista’, of which he would later take charge. He was arrested in 1938 and after a period of detention in Varese, was sentenced to five years’ confinement at Ventotene. With his wife Ursula, he supported the elaboration of Altiero Spinelli and Ernesto Rossi’s manifesto on the United States of Europe, to which he later wrote an introduction.

Escaping from confinement in Melfi, where he had been transferred with his family, Colorni moved to Rome and joined the Resistance. He was assassinated in May 1944 on the eve of the liberation of the capital.