When the Sanhedrin (the “Torah court” of ancient Israel) determined that the new moon had been sighted, marking the beginning of a new month, they spread the word through the building of a series of hilltop bonfires which could be seen by others further from Jerusalem. Why did they discontinue this system and instead begin using dispatched messengers?
A. After Constantine the Great, leader of the Roman Empire, converted to Christianity, the Sanhedrin determined that a public announcement of the new month via bonfires would draw undue attention to the Jews, leading to a possible effort by Constantine to convert them. Therefore, they discontinued the bonfires and began using messengers.
B. One of the bonfires spread out of control and destroyed the town of Shiloh, leading to the Sanhedrin's ban on bonfires.
C. As a result of climate change, the normally desert-like climate of ancient Israel became very humid and rainy. Torrential downpours were frequently preventing the building of bonfires, thus causing the Sanhedrin to make the change to dispatched messengers. (The Sadducess, who were climate-change deniers, continued to build bonfires despite the fact that they were regularly extinguished by monsoon-like rains).
D. This was an example of the difference between the House of Shammai and the House of Hillel. Shammai said that fires should be lit as a reference to G-d's announcement of the creation of the universe, "Vayehi Or (Let there be light)." Hillel said that messengers should be sent, as a symbol of the angels that G-d sent as messengers to the Patriarchs, Moses, Joshua, and other Biblical figures. As was generally the case, the opinion of Hillel took precedence.
E. The Sadducees, who did not recognize the rabbinic authority of the Sanhedrin, began setting bogus bonfires on the wrong date to manipulate the calendar.