what has changed since Yeats saw the swans for the first time

“All's changed,” since the speaker saw the swans for the very first time.(Yeats 14-15)

The life of Yeats has been changed. He saw the swans when he was only nineteen and was a young man. Now he has grown old with the passage of time. And because of the revolution in Ireland so many things has been changed in Yeats' life.

Nineteen years have passed and the speaker says that “All’s changed…” (line 15). It is clear that the speaker as ages,and with age, has gained life experience and also experienced massive changes in his life. The reference to change is an indicator of the growth of wisdom from innocence.