Abstract Summary
Arthur S. Eddington (1882-1944) certainly was one of the world’s most famous astronomers during the interwar period. For thirty years he was the director of the Cambridge Observatory and taught astrophysics at Trinity College. From 1916 onwards, he endeavored to develop a series of stellar models and a decade later he published his influential Internal Constitution of the Stars that Henry Norris Russell dared call “a work of art”. Besides the different steps that led Eddington to his famous mass-luminosity relationship in 1924, enlightened by some unpublished correspondence, this paper addresses some original views in terms of methodology. Indeed, Eddington purposely used trial and error, which he considered “as scientific as any other method”, the important point being to obtain physical insight on the problem one intends to tackle, and to keep mathematics “as the tool and not the master in physical research”.