For instance, if a man ceases to take any concern in worldly matters, conceives a distaste for common pleasures, and appears sunk in depression, the doctor will say, “This is a case of melancholy, and requires such and such prescription. The physicist will say, “This is a dryness of the brain caused by hot weather and cannot be relieved till the air becomes moist.” The astrologer will attribute it to some particular conjunction or opposition of planets. “Thus far their wisdom reaches,” says the Koran. It does not occur to them that what has really happened is this: that the Almighty has a concern for the welfare of that man, and has therefore commanded His servants, the planets or the elements, to produce such a condition in him that he may turn away from the world to his Maker.The knowledge of this fact is a lustrous pearl from the ocean of inspirational knowledge, to which all other forms of knowledge are as islands in the sea.
The Alchemy of Happiness, Imam Al-Ghazali