I found it!
The Family Reunion, a play by TS Eliot, was published in 1939. I probably read it when I started Honours English in my third year at University, in 1948. My copy cost $2.00. Can you imagine? I found the line instantly and I guess I didn't look it up in 2013 because it is slightly different from my memory's recollection:
"You all look so withered and young"
The idea is right on, though, that people wither and dry up but seldom mature.
Or even ripen.