Doing so requires some notational care. In many texts discussing charge conjugation, the involution ψ ψ ↦ ↦ ψ ψ c is not given an explicit symbolic name, when applied to single-particle solutions of the Dirac equation. This is in contrast to the case when the quantized field is discussed, where a unitary operator C is defined (as done in a later section, below). For the present section, let the involution be named as C : ψ ψ ↦ ↦ ψ ψ c so that C ψ ψ = ψ ψ c . Taking this to be a linear operator, one may consider its eigenstates. The Majorana condition singles out one such: C ψ ψ = ψ ψ . There are, however, two such eigenstates: C ψ ψ ( ± ± ) = ± ± ψ ψ ( ± ± ) . Continuing in the Weyl basis, as above, these eigenstates are