The mathematization of history needs all the class of possible histories, which all without only one are counterfactual or alterntive. The mathematical formalism of the separable complex Hilbert space of quantum mechanics can be applied to that mathemazable class similarly to the alternative Feynman pathways in quantum mechanics. One can infer an operator (non-Hermitian, in general) transforming our real historical pathway into any other thus being counterfactual to ours as real