Einstein Sees a Silver Lining

Or, at least, an unrelated happy event.

Here’s a line from one of his letters to a friend:

“The little one is very sickly and must go to Arosa [where there’s a sanatorium] for a year. My wife is also ailing. Worries and more worries. Nevertheless, I have found a nice generalization of the Sommerfield-Epstein quantum law.”