The only one of his extant works which is philosophical in content is the small treatise "Hegyon ha-Nefesh," Meditation of the Soul.[148] It is a popular work, written with a practical purpose, ethical and homiletic in tone and style. The idea of repentance plays an important rôle in the book, and what theoretical philosophy finds place therein is introduced merely as a background and basis for the ethical and religious considerations which follow. It may be called a miniature "Duties of the Hearts." As in all homiletical compositions in Jewish literature, exegesis of Biblical passages takes up a good deal of the discussions, and for the history of the philosophic movement in mediæval Judaism the methods of reading metaphysical and ethical ideas into the Bible are quite as important as these ideas themselves. The general philosophical standpoint of Abraham bar Hiyya may be characterized as an uncertain Neo-Platonism, or a combination of fundamental Aristotelian ideas with a Neo-Platonic coloring. Thus matter and form are the fundamental principles of the world. They existed potentially apart in the wisdom of God before they were combined and thus realized in actuality.[149] Time being a measure of motion, came into being together with the motion which followed upon this combination. Hence neither the world nor time is eternal. This is Platonic, not Aristotelian, who believes in the eternity of motion as well as of time. Abraham bar Hiyya also speaks of the purest form as light and as looking at and illuminating the form inferior to it and thus giving rise to the heavens, minerals and plants.[150] This is all Neo-Platonic. And yet the most distinctive doctrine of Plotinus and the later Neo-Platonists among the Arabs, the series of emanating hypostases, Intellect, Universal Soul, Nature, Matter, and so on, is wanting in the "Hegyon ha-Nefesh."[151] Form is the highest thing he knows outside of God; and the purest form, which is too exalted to combine with matter, embraces angels, seraphim, souls, and all forms related to the upper world.[152] With the exception of the names angel, seraphim, souls, this is good Aristotelian doctrine, who also believes in the movers of the spheres and the active intellect in man as being pure forms.