The clearest and most creative thoughts are those that occur during one of three states: the first is at the onset of sorrow, the second in bed just before falling asleep, and the third in the latrine. The last involves the breakdown of concentrated matters exhaled by the bowels and the intestines and this breakdown and exhalation taking place in the lower part has the effect of breaking down, at the same time and place, whatever may have coagulated in the higher folds of the brain. Some of this matter then departs in a downward direction while some of the images formed by the brain rise, like steam rising from the earth to thicken into a raincloud.
Ahmad Fāris al-Shidyāq, Leg over Leg, Volume Three.