BOSTON, MASS.- A letter written by physicist Albert Einstein to his son discussing his happiness with his work to solve the Unified Field Theory will be auctioned by Boston-based RR Auction.

The one page letter in German, signed “Papa,” undated but circa early 1929. Letter to his son Eduard Einstein, nicknamed “Tetel,” in full (translated): “Your letter made me very happy, particularly your comment regarding the hotel. Just like you, I hate it and it is with delight that I am detecting here a deep inner kinship between us, which I treasure. It seems to me it has been so long since I have seen you and I am longing to have you around me once again.

For Easter, Albert and his wife will be visiting here. You could be coming at the same time, no matter. I would make sure you have sleeping quarters at a friend’s house while Albert is here. By the way, there is still another hurdle. On the 14th of March I have to flee to escape from my 50th Birthday Party otherwise I would run the risk of perhaps getting seasick. But there is still a lot of time until Easter. At any rate, I certainly want to see you before you graduate from High School.

I am now very happy because I finally solved to my total satisfaction, after immensely intensive work, my gravitation-electricity problem. This, in a way, concludes my life’s work—the remainder simply is bonus material. Remarkably, how through all this strenuous work I made it in good shape and am feeling quite well. I do, however, practically live the life of a recluse and follow a frugal way of live. When we see each other again, I shall try to explain to you and describe this lifestyle a bit. In no way do I expect your approval and perhaps desire to join this guild. I could not care less.

Don’t get overwhelmed by that heavy volume of a book I sent you. One should read it in small segments, always keeping in mind that this represents chosen selections of intellectual work through the centuries, expressed by an unimportant, but decent and clear thinking human being.”

He adds a postscript, in full: “I have been reading with great admiration Bernard Shaw’s new book on Socialism and Capitalism. I will be sending it to you soon and strongly recommend you definitely read this remarkable book.”

In 1924, Einstein had finished laying the essential groundwork for his most complex and ambitious theory yet—the Unified Field Theory, an attempt to explain the nature of gravity in terms of the laws of electromagnetism.

After making further refinements, he published the theory in 1929. The ideas he put forward conflicted with the emerging understanding of quantum mechanics, which put him at odds with much of the physics community at large; these disagreements led to a famous falling out with fellow Nobel winner Niels Bohr.

Although he continued to work on the Unified Field Theory for the rest of his life, Einstein—despite his exuberance in the present letter—was never able to satisfactorily master the problem, and it remains unsolved to this day.

“Einstein does not usually talk about his life’s work— that’s what make’s the letter spectacular,” said Robert Livingston, Executive VP at RR Auction. “The letter reveals Einstein as both an accomplished physicist and caring father, this is a remarkable letter with simply extraordinary content.”

Among other items featured:

• Albert Einstein letter to the widow of New York Dr. Isidore W. Held, who was involved in helping Jewish intellectuals escape from Nazi Germany and published articles on behalf of persecuted Jewish physicians.

• Albert Einstein typed letter at the height of WWII, Einstein pledges “my influence” to a would-be Jewish refugee.

• Vintage glossy press photo of Einstein in a candid moment, signed in the lower border.

Online bidding for the Fine Autographs and Artifacts auction from RR Auction began on September 27 and will conclude on October 12.