The noble award winner signed the two-sided letter dated December 5, 1919 as "Albert" on one side and "Papa" on the other.
In beginning of the letter, Einstein talks about the arrangement of divorce to his wife Mileva Maric and the eduction of his son Hans Albert.
"It seems that we are condemned to a kind of gypsy-life. Under the present circumstances I can understand you very well... I also prefer, of course, that Albert will not have to change schools. Completing school as soon as possible is not a good enough reason," he wrote.
"I am pleased that you are taking lessons from Amberg. He is a very sympathetic man...He was an assistant to Hurwitz when I was a fledgling student; at that time I was tested by him in the Repetitozimmer. He was then quite young. Seiler was also an assistant in the Physics building when I was a student. I liked him less," Einstein wrote.
"This is an exceptional handwritten letter offering details related to both Einstein's personal family life and his scientific legacy," said RR Auction house.