The importance of previous papers by the legendary scientist has centred on mathematic formulae. But the letters, from the estate of his first wife, Mileva Maric, put him on what the auctioneers Christie's describe as "a human level" - even if some are written on the back of his scientific notes
They show that the mathematician was only 17 when he met the student Mileva, who he describes as his "kitten" and his "doll". His mother - who "threw herself on to her bed and wept" at the news that he was in love - accused him of ruining his future and destroying his opportunities. "By the time you are 30 she is an old witch," he quotes his mother as saying.
The correspondence shows that Einstein and Mileva were living together when in 1902 she gave birth to a daughter, Lieserl, while on holiday. Soon after her birth, Einstein wrote enthusiastically: "Is she healthy, and does she cry properly? What are her eyes like? Which one of us does she more resemble? Who is giving her milk? Is she hungry?
"I love her so much and don't even know her yet! Couldn't you have a photograph made of her when you've regained your health?"
But after only a few months, Lieserl mysteriously disappears from the correspondence. Einstein's last reference to his daughter was written when Mileva was in Serbia, pregnant with their first son.
He wrote: "I'm not in the least bit angry that poor Dollie [his pet name for Mileva] is hatching a new chick. In fact I'm happy about it and had already given some thought to whether I shouldn't see to it that you get a new Lieserl.
"I'm very sorry about what has befallen Lieserl. It's so easy to suffer lasting effects from scarlet fever. As what is the child registered? We must take precautions that problems don't arise for her later."
Lieserl's existence was first revealed 10 years ago. But despite research, the child's fate is not known and she is never referred to again by the couple. It is believed Einstein never saw her.
The papers, which will be auctioned in New York next month, are expected to fetch around pounds 2m. Felix de Marez Oyens of Christie's said they are of great importance to collectors.
"His human strengths and weaknesses come through, his interest in current affairs, his political interests, come through. They put him on a human level."Reuse content