Sidney Coleman (1937–2007) was a renowned theoretical physicist, who taught for more than forty years at Harvard University. He contributed critical work on quantum field theory, high-energy particle physics, and cosmology. He was also a remarkably effective teacher who introduced generations of physicists to quantum field theory, mentoring several leading members in the field. His sense of humor and wit became legendary. This selection of his previously unpublished correspondence illuminates changes in theoretical physics and in academic life over the course of Coleman's illustrious career. The letters show the depth of Coleman's activities and interests, including science fiction, space travel, and the US counter culture. The volume also includes Coleman's legendary lecture "Quantum Mechanics in Your Face."