In all the predictions of diviners or oracles, when they are followed by fulfilment, we can hardly disavow that the evil spirit intervenes, and discovers the future to those who consult him. St. Augustine, in his book _de Divinatione Daemonum_,[199] or of predictions made by the evil spirit, when they are fulfilled, supposes that the demons are of an aerial nature, and much more subtile than bodies in general; insomuch that they surpass beyond comparison the lightness both of men and the swiftest animals, and even the flight of birds, which enables them to announce things that are passing in very distant places, and beyond the common reach of men. Moreover, as they are not subject to death as we are, they have acquired infinitely more experience than even those who possess the most among mankind, and are the most attentive to what happens in the world. By that means they can sometimes predict things to come, announce several things at a distance, and do some wonderful things; which has often led mortals to pay them divine honors, believing them to be of a nature much more excellent than their own. But when we reflect seriously on what the demons predict, we may remark that often they announce nothing but what they are to do themselves.[200] For God permits them, sometimes, to cause maladies, corrupt the air, and produce in it qualities of an infectious nature, and to incline the wicked to persecute the worthy. They perform these operations in a hidden manner, by resources unknown to mortals, and proportionate to the subtilty of their own nature. They can announce what they have foreseen must happen by certain natural tokens unknown to men, like as a physician foresees by the secret of his art the symptoms and the consequences of a malady which no one else can. Thus, the demon, who knows our constitution and the secret tendency of our humors, can foretell the maladies which are the consequences of them. He can also discover our thoughts and our secret wishes by certain external motions, and by certain expressions we let fall by chance, whence he infers that men would do or undertake certain things consequent upon these thoughts or inclinations.