In the Mediterranean world there is nothing deader looking than the fig tree in winter. And for a season it appears dead and lifeless. But in the spring, as the days grow longer and warmer, the sap begins to rise. The lifeless tree stirs to life. Buds break out on tender twigs.
Leaves spring forth from bare branches.
The dry tree becomes green once again. It is a picture of life, resurrection, new creation. God is making everything new again. Just so, when you see the sun get dark, and the moon and the stars fade and fall, you will know that He is near, right at the threshold. Just when the world appears the deadest, it will burst full of life because it will be full of Jesus' life.