"You are old, Father William," the young man said,
"All your papers these days look the same;
Those William's would be better unread --
Do these facts never fill you with shame?"

"In my youth," Father William replied to his son,
"I wrote wonderful papers galore;
But the great reputation I found that I'd won,
Made it pointless to think any more."

40 isn't old. If you're a tree.