"Showers of blood, however dreadful, were not news. Pliny, Cicero, Livy, and Plutarch mentioned rains of blood and flesh. Zeus makes it rain blood, 'as a portent of slaughter,' in Homer's Iliad."
For millennia, showers of blood, known variously as blood falls, rains of blood, and blood rain, have been reported in sources both historical and literary. The earliest record comes from Homer’s Iliad, in which Zeus makes it rain blood “as a portent of slaughter”: “Then, touch’d with grief, the weeping Heavens distill’d / A shower of blood o’er all the fatal field.” Pliny, Livy, and Plutarch mention actual rains of blood and flesh. Cicero recorded these events as well, but doubted their veracity. Cicero, an early proponent of the view that these rains had a natural explanation, was succeeded in the twelfth century by “the great grammarian and natural philosopher” William of Conches, who sought to explain blood falls as the result of the power of wind and the properties of condensed and heated rain.