It is claimed that the current Magisterium relies on only one strand of the patristic tradition, and not on the whole legacy of the ancient Church. Although the Fathers clearly held fast to the doctrinal principle of the indissolubility of marriage, some of them tolerated a certain flexibility on the pastoral level with regard to difficult individual cases. On this basis Eastern Churches separated from Rome later developed alongside the principle of akribia, fidelity to revealed truth, that of oikonomia,