The poem " Song of rain " goes by stanza's - 
Stanza 1 - 
The poet writes that rain is sent on earth by the gods. nature welcomes rain to beautify her fields and valleys!
Stanza 2 -
He says he was once pearls on the crown of queen Ishtar ( ishtar means goddess of fertility, love, war, and sex )  but was plucked by the godess of dawn to embellish the earth!
Stanza 3 -
He says that when there is rainfall, all things are filled with joy and happiness!
Stanza 4 -
He says that the fields and clouds are its lovers because - it satisfies the need of water in the field , it lessen the heavy burden of the cloud!
Stanza 5 -
Before rainfall , thunder strike and announces the rains entry. the spotting of a rainbow shows its end!
Stanza 6 -
Rain has its roots in the sea ( evaporation). whenever it sees a dying field it showers water and rejuvenates flowers and tress!
Stanza 7 -
The pitter- patter against the window sill is always welcome but only few appreciate it!
Stanza 8 -
Heat causes evaporation and ultimately rainfall, rainfall however makes the atmosphere cool!
Stanza 9 and 10 -
It says it evaporates from the sea, makes fields happy and is the tears of heaven!