Despite Arab and Islamic influence (notably, Muslim Sufism and Arabic Neoplatonism), the cosmological, ethical, and eschatological discourses of Duties of the Heart are essentially Jewish in both content and character. The introduction distinguishes between overt ceremonial rituals and commandments performed by organs and limbs of the body (“duties of the limbs”)—such as prayer, charity, fasting, and so forth—and inward belief, intention, attitude, and feeling, which are accomplished by the human conscience. Each of the ten sections that follow highlights a specific duty of the heart, which serves as a gate through which the soul must ascend if it is to attain spiritual perfection. The ten gates are divine unity, divine wisdom and goodness as the foundation of creation and nature, divine worship, trust in God, unification of and sincerity in purpose and action in serving God, humility, repentance, self-examination, abstinence, and the love of God. Each duty of the heart is illustrated by both positive and negative precepts (for example, to attain nearness to God, to love those who love Him and to hate those who hate Him). All duties of the heart are informed by revealed Torah, tradition, and—especially—reason. Philosophical proofs are offered for the unity and incorporeality of God and for the creation of the world, including teleology and creatio ex nihilo. Total separation from the pleasures of the world is not encouraged; the recommended asceticism involves living in society and directing societal obligations toward the service of God. In summation, the communion of humanity and God is made possible by the duties of the limbs, but the further union of the soul of humanity with the “divine light” of God is by the synthesis of virtues gained by the duties of the heart. Bahya’s theological work, which is considered the most popular moral-religious work of the medieval period, has left an indelible mark on subsequent generations of Jewish ethical and pietistic writing.