source for this quote by Goethe on Schiller's death?

[landofnowhere]

Dear DW friends,

While reading the Memoir of Madame Jenny Lind-Goldschmidt, I came across this quote attributed to Goethe on the occasion of Schiller's death:

"It is good for us that he was taken in the fulness in the splendour of life, for mortals rest in our memory as they were when they left the earth. Therefore it is that Achilles remains with us, an ever-dying youth."

Can anyone help me find the original source for this?

Thanks,
landofnowhere