set o = the object of C2;
set m = the Morphism of the object of C2, the object of C2;
take C1 --> the Morphism of the object of C2, the object of C2 ; :: thesis: ( C1 --> the Morphism of the object of C2, the object of C2 is feasible & C1 --> the Morphism of the object of C2, the object of C2 is Covariant & C1 --> the Morphism of the object of C2, the object of C2 is Contravariant )
thus ( C1 --> the Morphism of the object of C2, the object of C2 is feasible & C1 --> the Morphism of the object of C2, the object of C2 is Covariant & C1 --> the Morphism of the object of C2, the object of C2 is Contravariant ) ; :: thesis: verum