For over a hundred years, subatomic matter has been studied by bombarding relativistic elementary particles on quasi-stationary nuclear matter, with the most precise information on fundamental forces and the size and shapes of atomic constituents coming from electron beams. Over the past fifty years, significant new discoveries have been made by exploiting spin, the quantum property of elementary particles characterized by a left- or right-handedness. There is a miniscule diAerence between the probabilities for scattering left- and right-handed electrons oA subatomic matter, which can be exploited to measure the neutral weak force between electrons and matter constituents, thus gaining new insights into nuclear size and the nature of quarks inside protons and neutrons, and to search for new forces. I will describe the evolution of key experiments that use this technique, emphasizing what we have learnt to advance nuclear and particle physics, and where we are headed in the future.