Richard Feynman is remembered as one of the greatest physicists of the 20th century — a Nobel Prize–winning pioneer of quantum electrodynamics. His professional persona was sharp, rational, and famously skeptical; he demanded proof, clarity, and mathematical elegance from the world. Yet his 1946 love letter to his late wife, Arline, reveals a completely different dimension of Feynman — one that is tender, vulnerable, and deeply human. In that letter, written more than a year