In an auction on Thursday by Profiles in History, a letter by Albert Einstein written to his one of the sons in 1945 explaining the link between the theory of relativity and the atomic bombs has been sold for $62,500.

The organizers said it was one of the 27 letters by Einstein. In all, they have made more than $420,000. Other things put up for the auctions included letters written by Einstein in the 1940s. These letters explained his views on God. The letter was a reply one to a man who asked. Two letters sold for $28,125 and $34,375.

Profiles in History founder Joseph Maddalena was of the view that the letters were gathered over many years by a seller. Joseph said Albert Einstein had spent a fair amount of time writing letters on topics, including God, son’s geometry studies, and a little toy steam engine that his uncle gave him when he was a boy.

Some letters were in English and others in German. Some of them are written in longhand and others on typewriters. The letters represent one of the largest collections of personal writings of Einstein that has offered for sale.

“We all know about what he accomplished, how he changed the world with the theory of relativity. But these letters show the other side of the story. How he advised his children, how he believed in God”, said Maddalena.