Maurice Goldhaber, together with Lee Grodzins and Andrew Sunyar at Brookhaven National Laboratory, publish in 1958 "Helicity of Neutrinos", an experiment directly measuring, for the first time, a fundamental property of the neutrino: its helicity, that is, whether its spin is aligned with or against its direction of motion. The experiment comes barely a year after Tsung-Dao Lee and Chen-Ning Yang theoretically proposed (1956) that parity — mirror symmetry — is not conserved in weak interactions, and after Chien-Shiung Wu experimentally confirmed it (1957) by observing that electrons emitted in the beta decay of cobalt-60 are preferentially emitted in one direction relative to the nuclear spin. Goldhaber's experiment goes a step further: through a combined analysis of the circular polarization and resonant scattering of gamma rays emitted after the orbital electron capture of europium-152, the three physicists determine that the neutrino has negative helicity, that is, it is always "left-handed" — its spin points opposite to its direction of motion — with no observed exception. The result quantitatively and definitively establishes the V-A (vector minus axial) nature of the weak interaction: the force governing beta decay acts only on left-handed particles (and right-handed antiparticles), a structural asymmetry with no analog in gravity, electromagnetism, or the strong interaction. The experiment, described today in virtually every nuclear and particle physics textbook for the elegance of its design, becomes a cornerstone for the modern understanding of the weak interaction and, decades later, of neutrino physics.