Finding the original source of a quotation from novelist Charles Morgan

“The art of living does not consist in preserving and clinging to a particular mood of happiness, but in allowing happiness to change its form without being disappointed by the change, for happiness, like a child, must be allowed to grow up.”

A couple of quick google searches brings me to thinkexist domains and such. A googlebooks search just brought me to collection of quotations volumes.

Any ideas?

Is he Charles Langbridge Morgan? I don’t have an answer, but need to know if this is your guy?

Yes.

Based on some other random googling, I think it’s in something called “English Retrospect” but can’t find much more on that other than the name.