Berachos 3a - Part 2

R' Eliezer in the mishna said that the zman for the evening shma ends with the end of "the first watch". The gemara now delves into what exactly this means.

The gemara first wants to know, how many watches are there in the night? Either there are 3 or 4. Now, if there are 3 watches, why not simply say that the zman ends 4 hours into the night (as 12/3=4)? And, if there are 4 watches, why not simply say 3 hours into the night (as 12/4=3)?

The gemara answers that really R' Eliezer holds there are 3 watches during the night. The reason why the mishna chooses to define the time in terms of watches is to teach you another chiddush. The chiddush is that just like there are watches in the heavens there are also watches on earth.

The gemara brings a baraissa to prove this idea that there are watches both in heaven and on earth:

Baraissa: R' Eliezer says that there are 3 watches in the night. At each mishmar Hashem roars like a lion. A pasuk in Yirmayhu 25 mentions this idea. And, a siman for the mishmaros is that in the first one a donkey neighs. In the second, dogs scream. In the third, a baby nurses and a wife speaks with her husband.