Thousands of letters, papers and photos relating to Mahatma Gandhi are expected to fetch more than US$1 million ($1.2 million) when they go under the hammer at Sotheby's in London next month.
The huge archive of letters, papers and photos reveals new details about Indian leader Mahatma Gandhi and his time in South Africa.
The documents belonged to Hermann Kallenbach - who became arguably Gandhi's closest friend, according to Sotheby's Dr Gabriel Heaton
"It includes letters by Gandhi to Kallenbach and many letters from Gandhi's sons - very intimate and personal letters covering many decades actually," he said.
Kallenbach, a German-born Jew, met Gandhi in South Africa, where the Indian leader spent more than 20 years of his life before returning to India permanently in 1915.
In the letters Gandhi addressed his friend as 'my dear lower house', signing off 'with love, upper house'.
Among the most illuminating documents are the dozens of letters written by Gandhi's sons providing details of his life in India.