I became so excited I wanted to telephone Leningrad and find out if it were true but the mathematicians here [in Berkeley] said not to — after all the world has waited 70 years without knowing the answer to Hilbert’s tenth problem, surely you can wait a few weeks more. Fortunately, I didn’t have to. On Wednesday, John McCarthy called from Stanford University to say that he had heard a lecture by Ceĭtin in Novosibirsk on your proof. I received his notes yesterday and now I know it is true, it is beautiful, it is wonderful.

— Julia Robinson to Yuri Matiyasevich, 22 February 1970

Julia Robinson was 50 years old when she learned that Yuri Matiyasevich had resolved Hilbert’s Tenth Problem. He was just 22; she had been pondering the problem almost since the time of his birth. In the letter quoted above she conveyed her ecstatic response to his achievement. The notes about the proof were sketchy, but long experience with Hilbert’s Tenth Problem allowed her to quickly fill in the details — and also to see just how close she herself had come to solving this iconic problem.

It would have been understandable had she felt envy, disappointment, anger. But her letter is entirely free of such emotions. And in her subsequent correspondence with Matiyasevich, comprising about 150 letters, one sees that the ardent sincerity of that first letter was a hallmark of her character. It set the tone for their collaboration and for the warm friendship they shared until her death in 1985, at the age of 65.1