The conception of God is thus spiritualized. But resurrection and the future life are also regarded as being much more spiritual in character than the present life. Such a conception is facilitated by the doctrine of the Gnostic Philosophy, that there are three or four worlds. One above the other in regular order rise the Earthly and Sensible World of Men, the World of Celestial Spirits, to which our Soul belongs, the World of Supra-celestial Angels, and lastly God himself, as the World of purest Light and most perfect Spirit. The pious and enlightened Soul ascends from the lower world through the heavens till it is face to face with God, for it is of spiritual nature and its resurrection-body is of celestial essence. In a manner corresponding to the different worlds and grades of Souls, men themselves differ from one another. The man of sensuous nature must be content with the Koran and Tradition: he should not venture beyond the letter of the Law. The study of duty is his bread of life; philosophy would be a deadly poison to him. He who cannot swim should not venture into the sea. However there are always people who go into the water for the purpose of learning to swim. They want to elevate their faith into knowledge, but in the process they may easily fall into doubt and unbelief. For them, in Gazali’s opinion, a useful remedy may be found in the study of Doctrine and Polemics directed against Philosophy. Those, however, have reached the highest degree of human perfection, who, without any laborious cogitation, experience in themselves by means of an inward and Divine illumination the truth and the reality of the Spiritual World. Such are the prophets and pious mystics, among whom Gazali himself may be reckoned. They see God in everything,—Him, and Him alone—, and in Nature just as in the life of their own Soul; but they see Him best in the Soul, for although it is not Divine it has at least a likeness to the Divine. How altered now is every outward thing! That which seems to be in existence outside of us, becomes a condition or a property of the Soul, which in the consciousness of its union with God, advances to the highest bliss. All things then become one in Love. The true service of God transcends fear of punishment and hope of reward, attaining to Love of God in the Spirit. The perfect servant of God is raised above endurance and thanksgiving,—which constitute the obligation of the pious wanderer upon the earth, so long as he remains imperfect—, so that even in this world he loves and praises God with joy of heart.