Moreover Bahya is the first, he tells us, among the post-Talmudical writers, to treat systematically and _ex professo_ this branch of our religious duties. When I looked, he says, into the works composed by the early writers after the Talmud on the commandments, I found that their writings can be classified under three heads. First, exposition of the Torah and the Prophets, like the grammatical and lexicographical treatises of Ibn Janah, or the exegetical works of Saadia. Second, brief compilations of precepts, like the works of Hefez ben Yazliah and the responsa of some geonim. Third, works of a philosophico-apologetic character, like those of Saadia, Al Mukammas and others, whose purpose it was to present in an acceptable manner the doctrines of the Torah, to prove them by logical demonstration, and to refute the criticisms and erroneous views of unbelievers. But I have not seen any book dealing with the "hidden wisdom."[110] Here we see clearly the purpose of Bahya. It is not the rationalization of Jewish dogma that he is interested in, nor the reconciliation of religion and philosophy. It is the purification of religion itself from within which he seeks to accomplish. Sincerity and consistency in our words and our thoughts, so far as the service of God is concerned, is the fundamental requirement and essential value of the duties of the heart. To be sure this cannot be attained without intelligence. The knowledge of God and of his unity is a prerequisite for a proper understanding and an adequate appreciation of our religious duties. Philosophy therefore becomes a necessity in the interest of a purer and truer religion, without reference to the dangers threatening it from without. Having found, he continues in the introduction to the "Duties of the Hearts," that all the three sources, reason, Bible and tradition, command this branch of our religious duties, I tried to think about them and to learn them, being led from one topic to another until the subject became so large that I feared I could not contain it all in my memory. I then determined to write the subject down systematically in a book for my own benefit as well as for the benefit of others. But I hesitated about writing it on account of my limitations, the difficulty of the subject and my limited knowledge of Arabic, the language in which I intended writing it because the majority of our people are best familiar with it. But I thought better of it and realized that it was my duty to do what I could even if it was not perfect; that I must not yield to the argument springing from a love of ease and disinclination to effort; for if everyone were to abstain from doing a small good because he cannot do as much as he would like, nothing would ever be done at all.