Al-Ghazali — Lettre à un émir

The disorders of the human organism which is the most intricate and complex structure in the world, and the exact means of putting them right are the most difficult and complex study, and in being so they yield a large scope for fallacies of observation and inference. Therefore, there are many false theories and many monstrous remedies for them. So many and great errors and evils have flowed from wrong observation and reasoning therefore it is only natural for me to be full of worry. The physicians who try to cure these diseases, as if they proceed from natural causes, are ignorant people who know nothing of medicine. The truth of the matter is that the One who creates diseases is the One who knows how to cure them, but common people believe that medicine should be bought from a pharmacist, according to the prescription of a physician, and then used as directed. This is the most serious error. It is through the mercy and guidance of Allah, the Almighty, that the patient selects the most suitable doctor for his treatment and again it is through Divine Revelation that the physician prescribes the best remedy, taking into account the suitable quantity and quality of medicine which is to be used with due regard to time and interval, for if a doctor ignores these important factors, he is of no use to the patient who will ultimately abandon his treatment as useless or pernicious. The best and most reliable medicines are not obtained from shops or pharmacies, because the key to them lies in the treasure of the angels who are the agents responsible for the administration of the affairs of the kingdom of heaven.…