Mistake in the interpretation of the Law is thus of two kinds--a mistake which can be excused in one fit to look into the thing in which it has been committed, just as an expert physician is excused if he commits an error in the application of his science; or a magistrate when he misjudges, and a mistake which is inexcusable in one not fit to investigate a thing. But the error which cannot be excused for anybody, and which, if it happens to show itself in relation to the very principles of the Law, is infidelity, and if in universals is an innovation, is that error which is committed in those things which have been settled by all arguments and so the knowledge of them is possible for everybody, for instance, the acknowledgement of the existence of God, of Prophecy, and of the happiness or the misery of the next world. This is so, because all these three principles are proved by those three methods, the justification of which a man cannot deny by any means, that is exhortative controversial and argumentative proofs. A denier of such things, which are the very root of the principle of the Law, is an unbeliever, a retrograde with his tongue and his heart, or through negligence, on account of his denying them in spite of proofs. For if he be a man believing in arguments, he can verify them through these or if he believes in controversy, he can verify through that; and if he believes in religions admonitions he can well justify them through these. And hence the Prophet has said: “I have been commanded to fight with men till they say: ‘There is no God but Allah’ and believe in me” that is, by any of these three means of attaining the Faith. But there are things which, on account of their obscurity, cannot be understood by inference. So, God has favoured such of his creatures as cannot understand logic, either on account of their nature, habit, or lack of mental training, by quoting examples and parables of such things and has urged them to testify as to their truth through them. For everyone has mental capacity enough to understand them by the help of dogmatic and exhortatory argument which are common to all men. This is why the Law has been divided into two kinds: exoteric and esoteric. The exoteric part consists of those examples which have been coined to express certain meanings; while the esoteric is the meanings themselves, which are not manifested except to the learned in philosophy.