  In the review article in Progress in Particle and Nuclear Physics
(vol.121(2021) 103890)) the authors present the achievements so far of the
spin-charge-family theory, which offers the explanation for all the so far
observed properties of elementary fermion and boson fields, if the space-time
is higher than d=(3+1), it must be $d\ge (13+1)$. Fermions interact with
gravity only. Ref. PPNP (vol.121(2021) 103890)) presents, in addition to a
rather detailed review of all the achievements of this theory so far, also an
explanation for the postulates of the second quantization for fermionic fields:
The internal space of fermions described with "basis vectors" represented by
the Clifford odd objects manifests all the properties of fermion fields,
including the anticommutativity of their creation and annihilation operators.
This paper shows that even Clifford algebra objects provide a description of
the internal space of boson fields manifesting all known properties of boson
fields, explaining as well the reasons for the second quantization postulates
for boson fields. Properties of fermion and boson fields with the internal
spaces described by the Clifford odd and Clifford even objects are demonstrated
on the toy model with $d=(5+1)$.
