Who said "Gratitude opens the door to joy."?

This quote is attributed to Anaxagoras.

Gratitude opens the door to joy. - Anaxagoras

"Gratitude opens the door to joy."

Anaxagoras Gratitude

Philosopher Ancient Greece 500–428

"Appearances are a glimpse of the unseen."

"Mind is the finest thing that exists."

"Everything has a natural explanation."

"The greatest things are the smallest."

"Gratitude makes life richer."

"A grateful heart is a happy heart."

"Respect those who came before us."

"Life's greatest treasures are the people we love"