Who said "Change is the only constant in this world."?

This quote is attributed to Rhaegar Targaryen.

Change is the only constant in this world. - Rhaegar Targaryen

"Change is the only constant in this world."

Rhaegar Targaryen Change

"The dragon has three heads."

"I have a duty to my realm and to the future."

"Music is the voice of the soul."

"Love is the most powerful force in the world."

"Change brings new opportunities."

"Every day is a new opportunity."

"Healing doesn't mean forgetting."

"You either get better or you get bitter."