Now it must be asked if we can comprehend why comets signify the death of magnates and coming wars, for writers of philosophy say so. The reason is not apparent, since vapor no more rises in a land where a pauper lives than where a rich man resides, whether he be king or someone else. Furthermore, it is evident that a comet has a natural cause not dependent on anything else; so it seems that it has no relation to someone's death or to war. For if it be said that it does relate to war or someone's death, either it does so as a cause or effect or sign.
De Cometis