“You expected to be sad in the fall. Part of you died each year when the leaves ...

“You expected to be sad in the fall. Part of you died each year when the leaves fell from the trees and their branches were bare against the wind and the cold, wintery light. But you knew there would always be the spring, as you knew the river would flow again after it was frozen. When the cold rains kept on and killed the spring, it was as though a young person died for no reason.”

― Ernest Hemingway, A Moveable Feast

According to the passage, what is the implied significance of the river flowing again after being frozen?