Bahya connects his theory with the three souls of Plato, and likewise ascribes to the soul an ethereal essence.(931) He holds that its destiny is to raise itself to the order of the angels through self-purification, and finally to return to God as the divine Source of light. To this end the intellectual soul, which has its being from the primal light, must overcome the lower sensuous soul which leads to sin.
6. The conception that the soul is a substance derived from the luminous primal matter, like the heavenly spheres and the angels, was now persistently retained by the Jewish thinkers, who explained thereby its immortality. In adopting the Aristotelian theory that the soul is the form-principle of the body, the Platonic doctrine of its preexistence was gradually relinquished, and its existence ascribed to a creative act of God at the birth of the child or at its conception. But Jehuda ha-Levi, the most pious of all the philosophers, emphasized vigorously the indivisibility of the soul, its incorporeality and its reality apart from the condition of the body, and--in opposition to the Aristotelian free-thinkers, who expected the human soul to be absorbed into the divine soul, the active intellect,--he declared the immortality of the individual a fundamental article of faith.(932)
Now some of the Jewish thinkers, following Jehuda ha Levi, Ibn Daud, and others, though Aristotelians, shrank from the logical conclusion of denying all individuality to the soul, and attributed to it rather a process of purification, which ends with the elevation of the soul-essence to angelic rank and thus guarantees its immortality. Not so Maimonides, who accepted with inexorable earnestness the Aristotelian idea of form as the perfection of matter. The essence of the human soul is, for him, that force or potentiality which qualifies it for the highest development of the intellect, and is alone capable of grasping the divine. Yet it can acquire a part in the creative World-spirit only in the same degree as it unfolds this potentiality to share the divine intellect, whose seat is the highest sphere of the universe. By dint of this acquired intelligence it can live on as an independent intellect, in the image of God, and thus attain beatitude in the contemplation of Divinity.(933)