Not only does he classify believers in this careful way, but he also discusses the question, in the first book of his _Ihya_, whether Islam is the same thing as _iman_ (faith) or not, and if these two are not the same thing, can they exist separately or must they necessarily be combined? “Some say that Islam and _Iman_ are synonymous terms and that consequently every believer is a Moslem and every Moslem a believer.” This is the opinion held by the orthodox school. Others say that they are distinct things but joined together. Al-Ghazali answers this difficult question in this way: _Iman_ (Faith), from the linguistic point of view, means belief, intellectual conviction and assent; Islam means submission, subjection, obedience. The seat of _Iman_ is the heart or mind, and the tongue is its interpreter. Islam comprises belief with the heart and confession with the tongue, and good works by the members of the body, and is consequently a more comprehensive term than _Iman_. _Iman_ is one of the component parts of Islam, and Islam, therefore, includes it; but _Iman_, being a more restricted term, does not include Islam. From a linguistic point of view the two terms are therefore not synonymous. From the point of view of the law and religion, and in a theological sense the two terms are sometimes used as being synonymous, and sometimes as having different meanings and as being intermingled, comprised in each other. _Iman_ and Islam are found in the individual who believes in his heart and outwardly observes the precepts of Islam; Islam exists separately in the individual, who only believes in his heart; but neither confesses, nor does good works, and Islam exists separately in him who outwardly observes the precepts of Islam, without inner belief. What the faith of Islam meant to Al-Ghazali we know from all his works, especially from the _Ihya_, which besides other topics gives a full exposition of Moslem belief in regard to the six articles of their creed and the five pillars of practice. The reader may judge for himself both the contents and omissions of Al-Ghazali’s _credo_ from the following brief exposition which he wrote for his pupils: HIS CREED[54]