A reference to the Aristotelian 'demonstration' by strict logical reasoning from necessary truths, as laid down in the Posterior Analytics. This chapter goes to set aside the notion that unsound theology may still be sound philosophy. But as a truth, undiscernible by reason, may be discerned by revelation, so also may an error, or a flaw in an argument, be evident on grounds of revelation only, and not on any other grounds, where the argument is complicated and the matter removed from every-day experience, as in many Old Testament difficulties.