The Duties of the Heart, by Rabbi Bachye, tr. by Edwin Collins, , at sacred-texts.com
The supreme benefit, and the highest good bestowed by the Creator on human beings (after the gift of existence and the perfected faculties of perception and intelligence), is Wisdom. This, indeed, is the very life of their spirits. It is the lamp of their reason, which enables them to come to the will of God, and delivers them from all disaster in this world and in the world to come.
This Wisdom, or Philosophy, is of three kinds: the Philosophy of Nature, dealing with the properties and accidents of Matter; the Philosophy of Number and Measurement, the Mathematical Wisdom, including Astronomy and Music; and Philosophy, properly so called, including the knowledge of God, and the knowledge of His laws, and the rest of the sciences that are concerned with life and mind, and with human souls and spiritual beings. But all divisions of Wisdom are gates which the Creator, Blessed be He, has opened to human beings to enable them to attain to religion and the
world. Only some of these sciences are more necessary to the subject of Religion, and other divisions are more necessary for the attainment of worldly advantage. The highest form of Wisdom, the Divine Wisdom, is that which is most necessary to Religion. It is our duty to study this philosophy, in order, by means of Reason and discriminating intelligence, to attain to our religion, to morality and the laws of life that make for the health of our bodies and our souls. *
16:* The word here used is Torah (see note on p. 17).