I think in a way the world owes him and his memory a tremendous amount of gratitude.

Gratitude changes the pangs of memory into a tranquil joy

Gratitude is the memory of the heart.

I remember those happy days and often wish I could speak into the ears of the dead the gratitude which was due to them in life and so ill-returned.

Gratitude is the conscience of memory

Gratitude changes the pangs of memory into a tranquil joy.