Given that she had had a two-year affair with the married Albert Einstein when she was 23 and he was 44, and that she was a Jew desperate to escape an Austria overrun by the Nazis, what resounds down the years about the letter Betty Neumann sent to Einstein in America is its restraint and delicacy.

Writing to the already world famous scientist in German two months after Hitler's tanks had rolled into Vienna, Miss Neumann, by now in her mid-thirties, formally addresses her former lover – now installed at Princeton University – as "Highly Esteemed Herr Professor".

"Thinking about the time which was 15 years back, gives me confidence that you will maybe help me now," she writes. "I have lost my livelihood. My position as an X-ray assistant in a hospital, which I had for 10 years, has ended." She says that "maybe it will be known" to the Nobel laureate that both her parents are dead and that "nobody can take care of me." She adds: "In Europe all states are closed to immigrants so I must think of America."

The plea from Ms Neumann sent on 16 May 1938 was answered. Einstein, who was already revolutionising physics with his theory of relativity by the time his affair with Ms Neumann had started during his second marriage, wrote an affidavit which saved her.

And thanks to a digitisation programme unveiled yesterday by Hebrew University, of which the great theoretical physicist was a founder and lifelong supporter, her handwritten letter, in all its emotional immediacy, will soon be available online. It will join 81,000 other items in the formidably rich Einstein archive - including his plan for a lasting Jewish-Arab peace.

From today, internet users across the world will see some of 2,500 digitised items. They range from the original 1925 manuscript version of his completed General Theory of Relativity to a postcard sent by Einstein to his ailing mother Pauline on 27 September 1919.

Written just after he had heard that astronomers observing the previous May's solar eclipse in West Africa had seen "star displacements at the sun's edge" thus reinforcing a key prediction in his developing theory, it says "Dear Mother, Good news today... N A Lorenz has telegraphed me that the British expeditions have definitely confirmed the deflection of light by the Sun. Unfortunately Maja has written me that you're not only in a lot of pain but that you also have gloomy thoughts. How I would like to keep you company again so you're not left to ugly brooding."

The digitisation project is funded by the UK-based Polonsky foundation and thanks to co-operation with the Princeton University Press and the Einstein Papers Project at the California Institute of Technology, some of the documents will also be transcribed and translated.

Physicists and historians will naturally be drawn to the thousands of documents relating to the general theory. But interest will also be focused on the clear evidence that Einstein's support for a Jewish homeland was tempered a fervent and lifelong desire for peace with Arabs in the Holy Land.

"He was a Zionist but be careful how you use the word," Roni Grosz, curator of the Einstein Archive, said yesterday. "He had his own views on what Jews should and shouldn't do and about how they interact with their Arab neighbours."

As late as 1947 Einstein was doubtful about the idea of a state of Israel, though he supported it after its establishment the following year, and indeed on his deathbed was composing a broadcast for its seventh anniversary. But he refused the invitation to become its first President on the grounds that while he would be free as a private citizen to disagree with any future policy, as President he would not.

The full flavour of his thinking is conveyed in his correspondence during the British mandate with Azmi al- Nashashibi, the Arab editor of the newspaper Falastin, which had reported Einstein's theory while disparaging growing Jewish immigration. Einstein responded in December 1929 by writing that he had long been convinced that the future must be built on "an intimate community of nations."

He added: "I had therefore expected that the great Arab nation would more fully appreciate the Jewish need for restoring its national home in Judaism's old homeland. I am convinced that the loving interest which the whole of Jewry takes in the land of Palestine can be of benefit to the entire population of the country... I think the two great Semitic peoples that have made each in its own way lasting contributions to the civilization of the modern Western world can have a great future in common and that instead of facing each other with unfruitful hostility and mutual distrust they should... seek for the possibility for sympathetic co-operation."

By 1930, Einstein was on warm enough terms with the Palestinian editor to share with Falastin's readers his chosen peace process – one which firmly excluded politicians. Instead he envisaged a council of two four-strong teams, Jewish and Arab, working in secret, each of a "physician elected by the medical body; a jurist elected by the lawyers; a worker representative elected by the unions; and one clerical man elected by the ecclesiastical body". Each would undertake not to act out of sectional or national interest but "to take into account... according to their knowledge and conscience the prosperity of the whole inhabitants of the Land."

When three on each side agreed on a resolution they could make it public. Saying that "aggressive nationalism must be subdued," he asserts that the council would gradually "lead to a state in which differences will gradually be eliminated and common representation of the interests of the country will be upheld". Einstein summed up his vision of a future Palestine "only as the scene of peaceful co-operation between the two peoples whose land it is".