Who said "Nothing is permanent; even fear passes with time."?

This quote is attributed to Courage the Cowardly Dog.

Nothing is permanent; even fear passes with time. - Courage the Cowardly Dog

"Nothing is permanent; even fear passes with time."

Courage the Cowardly Dog Death

"Courage, the cowardly dog."

"What's wrong, Muriel?"

"Oh, the things I do for love."

"Stupid Eustace!"

"Death doesn't scare me anymore."

"Death and I are old friends."

"Welcome to my world."

"Death is just the beginning."