Use the following excerpt from boccaccio's the decameron to answer the following question:

"in the year of our lord 1348, there happened at florence, the finest city in all italy a most terrible plague; which, whether owing to the influence of the planets, or that it was sent from god as a just punishment for our sins, had broken out some years before in the levant (middle east) and, after passing from place to place, and making incredible havoc all the way, had now reached the west…"
public domain

how does boccaccio let you know that he recognized that the plague spread widely from one location to another?