Answer the question from the given passage. Your answer should be directly extracted from the passage, and it should be a single entity, name, or number, not a sentence.
Q: Passage: Medical knowledge had stagnated during the Middle Ages. The most authoritative account at the time came from the medical faculty in Paris in a report to the king of France that blamed the heavens, in the form of a conjunction of three planets in 1345 that caused a 'great pestilence in the air'. This report became the first and most widely circulated of a series of plague tracts that sought to give advice to sufferers. That the plague was caused by bad air became the most widely accepted theory. Today, this is known as the Miasma theory. The word 'plague' had no special significance at this time, and only the recurrence of outbreaks during the Middle Ages gave it the name that has become the medical term. Question: What is the newer, more widely accepted theory behind the spread of the plague?
A:
That the plague was caused by bad air