  We briefly review the main methods for the description of massive Weyl fields
in vacuum. On the classical level we discuss Weyl fields expressed through
Grassmann variables as well as having spinors with commuting components. In
both approaches we quantize the system. We get the correct anticommutation
relations between creation and annihilation operators, which result in the
proper form of the total energy of the field. However, the commuting classical
Weyl fields require the new method of quantization.
