At several points in this poem, Cummings mentions the four seasons almost out of nowhere. In line 3, for example, he breaks from his story about "anyone" to simply say, "spring summer autumn winter" (3). This reference to the seasons instantly throws us into nature's yearlong cycle, which also makes us think about time passing. But there's something very special about using seasons to mark the time. For starters it connects human life to nature. Second, it takes away the fantasy that human life is filled with constant progress into the future.
Cummings wants to remind us that life actually isn't about progress. It's just a circle that keeps going round and round. Later in the poem, Cummings mentions the seasons again but changes the order of them: "summer autumn winter spring" (34). Now it looks like the four seasons have shifted. But it's important to remember that there's no progress here. It's still the same four seasons going in a circle just like human life goes in circles, with birth, life, and death over and over.
Line 3: Cummings mentions the four seasons to give us a sense of time passing in a constant cycle
Line 34: Cummings returns to the four seasons with a slight difference, but only to remind us that the difference doesn't really matter. The cycle is still a cycle.