Albert Einstein is the rare figure who’s universally known, but almost entirely for his professional achievements. Few of us who can explain the theory of relativity can also say much about the personal life of the man who came up with it, though that doesn’t owe to a lack of documentation. Thanks to science YouTuber Toby Hendy, we have, for example, some of the love letters he wrote to the women who constituted a veritable parade through his life. Also, in another video for her channel Tibees, Hendy reads the letters he wrote in the process of divorcing his first wife, the Serbian physicist and mathematician Mileva Marić.Einstein married Marić in January 1903, says Hendy, “after they had been together for around five years. The relationship was in its prime, and so was the academic productivity. It was in 1905 that Einstein would publish his four major papers that would change the face of physics. By 1912, however, Einstein had started having an affair with his cousin,” Elsa Lowenthal.By 1914, Einstein wrote to Marić a letter “detailing some conditions of them continuing to live together,” if not quite as man and wife. The conditions read as follows:CONDITIONSA. You will make sure:1. that my clothes and laundry are kept in good order; 2. that I will receive my three meals regularly in my room; 3. that my bedroom and study are kept neat, and especially that my desk is left for my use only.B. You will renounce all personal relations with me insofar as they are not completely necessary for social reasons. Specifically, You will forego:1. my sitting at home with you; 2. my going out or travelling with you.C. You will obey the following points in your relations with me:1. you will not expect any intimacy from me, nor will you reproach me in any way; 2. you will stop talking to me if I request it; 3. you will leave my bedroom or study immediately without protest if I request it.D. You will undertake not to belittle me in front of our children, either through words or behavior.Though they agreed to put this stringent plan into effect, less than two weeks later, he wrote to Elsa, “Yesterday my wife left for good with the children” — and “you, dear little Elsie, will now become my wife and become convinced that it is not at all so hard to live by my side.”Einstein did marry Lowenthal in 1919, and the union, though hardly characterized by ideal faithfulness, did last until her death in 1935. There would be plenty of other women, but none who played quite the same role in his life as Marić, not only the mother of his children, but also — according to some historians — a collaborator on some of his accomplishments in physics. According to Lost Women of Science, “there is little tangible evidence to support the claims that Marić was a co-author of Einstein’s first major work. That said, there are plenty of personal testimonies from those who knew Marić and Einstein that her involvement was likely.” One condition of their divorce settlement, at any rate, held that Marić receive his Nobel Prize money, were he to win it, which he went on to do a couple of years later. This makes clear that, whatever the importance of her own scientific work, she must’ve had a good head on her shoulders.Related Content:Hear Readings of Albert Einstein’s Love Letters (and Chilly Divorce Letters) to His First Wife MilevaAlbert Einstein Imposes on His First Wife a Cruel List of Marital DemandsAlbert Einstein & Sigmund Freud Exchange Letters and Debate How to Make the World Free from War (1932)Read the Uplifting Letter That Albert Einstein Sent to Marie Curie During a Time of Personal Crisis (1911)“Do Scientists Pray?”: A Young Girl Asks Albert Einstein in 1936. Einstein Then RespondsAlbert Einstein’s Grades: A Fascinating Look at His Report CardsBased in Seoul, Colin Marshall writes and broadcasts on cities, language, and culture. His projects include the Substack newsletter Books on Cities and the book The Stateless City: a Walk through 21st-Century Los Angeles. Follow him on the social network formerly known as Twitter at @colinmarshall.