This book presents a collection of texts by the German physicist and philosopher Carl Friedrich von Weizs cker (1912-2007), for use in seminars on the history, epistemology and structure of physics. Most texts appear in English for the first time. Weizs cker became famous through his works in physics, mainly in the early development of nuclear physics. Later he would also become well known as a philosopher and analyst of contemporary culture. Texts include the original publications of the "Weizs cker-Bethe formula" of nuclear masses and the "Bethe-Weizs cker cycle," which explains the source of energy in the sun; both were developed by Bethe at the same time and independently of Weizs cker. Further texts deal with Weizs cker's explanation of the origin of planets, his explanation of the "time arrow" in Statistical Mechanics and his analyses of Quantum Mechanics and the structure of physics in general.