Albert einstein
Reuters

Famous physicist Albert Einstein's letters written to his sister and other collections such as postcards and rare photographs of his childhood will go on auction at Christie's in May, said local media.

The collections, preserved by Einstein's younger sister Maria Einstein, include some of the letters written by the scientist to her and one letter addressed to his father. The letters have some personal views which he never told people in the public, said an official at Christie's.

"He says some things that I've never seen him say anywhere else, and I've catalogued many hundreds of his letters," Thomas Venning at Christie's told the Guardian.

The letters are "unpublished snapshots of Einstein," reflecting Einstein's private face, while he is known to the world as a low-key and humble scientist, he said adding that they will be valued at 6,000 to 9,000 British pounds ($8,386 to $12,579).

In one letter, Einstein was quoted to have written to his sister Maria saying, "I am becoming very much loved and even more envied. There's nothing to be done about it." In another, he wrote, "the brain gradually goes off with age."

On his accomplishments, the world renowned scientist wrote that they had "become part of the foundations of our science." The letters were written by the German-born scientist who migrated to the United states between 1897 and 1951. Most of them were not published still, said the auctioner. Prior to the auction from May 2 to 9, the letters will be publicly exhibited from April 18 to 20, said Venning.

Einstein's pipe
Einstein's pipe (Christie's) Christie's

Christie's has sold several Einstein's collections in the past, including his smoking pipe, on which he once quipped: "I believe that pipe-smoking contributes to a somewhat calm and objective judgement in all human affairs." Einstein's billiard briar pipe, shown above, was sold for £52,500 on July 12, 2017 at Christie's in London.