In this section, Ettore Majorana discusses the possibility of achieving a complete formal symmetry in the quantum theory of electrons and positrons using a new quantization process. He argues that the equations of Dirac, which describe the states of negative energy, are modified by this new approach, eliminating the concept of negative energy states and the assumption of corresponding "antiparticles" for neutral particles. Majorana proposes a more direct method to achieve symmetry, which not only advances the formalism for electrons and positrons but also removes the notion of negative energy states, making it possible to construct a theory of neutral elementary particles without negative energy states. The new quantization process, inspired by the Jordan-Wigner method, generalizes the variational principles used in quantum electrodynamics, ensuring that the variables in the Lagrangian have their final meaning from the start, thus avoiding the need for classical interpretations. This approach is particularly significant for Fermi statistics and provides a natural framework for theories of neutral particles like neutrons and hypothetical neutrinos.In this section, Ettore Majorana discusses the possibility of achieving a complete formal symmetry in the quantum theory of electrons and positrons using a new quantization process. He argues that the equations of Dirac, which describe the states of negative energy, are modified by this new approach, eliminating the concept of negative energy states and the assumption of corresponding "antiparticles" for neutral particles. Majorana proposes a more direct method to achieve symmetry, which not only advances the formalism for electrons and positrons but also removes the notion of negative energy states, making it possible to construct a theory of neutral elementary particles without negative energy states. The new quantization process, inspired by the Jordan-Wigner method, generalizes the variational principles used in quantum electrodynamics, ensuring that the variables in the Lagrangian have their final meaning from the start, thus avoiding the need for classical interpretations. This approach is particularly significant for Fermi statistics and provides a natural framework for theories of neutral particles like neutrons and hypothetical neutrinos.