The cement plant is still a very important enterprise. The first dry season begins, and no one wants the job of sweeping the roof. So that job is eliminated. Everyone is certain that it is not important. And through the dry months cement dust builds up on the roof to a depth of several inches.
Rainy season begins.
With the first rains the dust turns to stone, and the roof collapses. Sweeping the dust off the roof during dry season was important. Israel had been delivered from Egyptian slavery. While they were in the wilderness, God gave them laws through Moses. You shall love the Lord your God with all your heart and with all your soul and with all your might.