EINSTEIN ALBERT: (1879-1955) German-born theoretical physicist, Nobel Prize winner for Physics, 1921. A.L.S., Albert, one page, 4to, n.p. (Berlin), 27th March 1931, to his first wife, Mileva Maric, in German. Einstein reports that he is thankful to have returned home again ?from the whirlwind that is America?, and informs Maric ?Despite a thorough search, we were unable to find the cacti. At last we have obtained this information: rare cacti are being brought in from Erfurt?. Einstein further writes of their eldest son, ?I would very much like to contribute to Albert?s move, but I prefer to entrust the money to you, as I have particular confidence in your financial management skills?, also remarking of his present work, ?I am working hard and enjoying the (relative) tranquillity of Berlin. Still on the subject of parallel-structured space?, and further mentioning their other son, ?I am always very pleased to hear news of Tetel. Tony has also spoken to me enthusiastically about him and is delighted to have made his acquaintance?. One small, neat split to the right edge of the central fold, not affecting the text, otherwise VG

Mileva Maric (1875-1948) Serbian mathematician, the first wife of Einstein from 1903-19. The couple had two sons, both referred to in the present letter, Hans Albert (1904-1973) and Eduard (1910-1965) who was affectionately known as Tetel.

Einstein?s reference to having recently returned from America relates to his first visit to the California Institute of Technology, Pasadena, where he spent January and February 1931 as a visiting scientist. During his stay he engaged with leading physicists and astronomers, including Edwin Hubble and Richard Chace Tolman, discussing the cosmological implications of the emerging evidence for an expanding universe. His visit also attracted considerable public attention, and he gave several public addresses, including a speech at the dedication of the Pasadena Junior College astronomy building on 26th February 1931. He returned to Europe shortly afterwards.

Einstein's mention of ?parallel-structured space? concerns his work on the theory of distant parallelism (Fernparallelismus), or teleparallelism, which he was pursuing in the early 1930s as a possible extension of general relativity and a means of unifying gravitation and electromagnetism. The theory introduced an additional geometrical structure into space-time, allowing vectors at different points to be compared by means of a notion of absolute or distant parallelism. Einstein published several papers on the subject in 1930?31, although he subsequently abandoned the approach as incompatible with the experimental and theoretical evidence.