Which explains the swallow's reason for visiting the statue the first time in "the happy prince"?

The statue of the Happy Prince stood on a high pillar in the city square. A swallow was flying to Egypt where his friends had already gone because the Statue's feet. Though the sky was clear, drops of water fell on the bird. He looked up and found the Prince was weeping. The swallow was wondering what was the prince sad about, and the Prince said that whilst he was alive he was not sad.It greatly saddened him how miserable his people were. His Heart was made of lead but he could not help weeping.