One of the most captivating aspects of Elon Musk’s testimony on Tuesday in his lawsuit against OpenAI was not the charity he alleges was taken from him (that was expected). It revolved around an old acquaintance.

Musk stated that a significant motivation behind co-founding OpenAI stemmed from a disagreement with Google’s Larry Page regarding AI safety — specifically, a discussion where Musk mentioned the possibility of AI extinguishing humanity, and Page dismissed it with a “fine,” as long as AI survived. Page labeled Musk as a “speciest” for being “pro human.” Musk deemed this perspective “insane.”

This is particularly noteworthy considering how close they used to be. Fortune listed them in its 2016 compilation of discreetly closest business friends; Musk was so at ease with Page that he frequently stayed over at his Palo Alto residence. Page once mentioned to Charlie Rose that he preferred to donate his money to Musk rather than to charitable causes.

Their friendship could not withstand the formation of OpenAI. When Musk enlisted Google AI expert Ilya Sutskever to aid in establishing the company in 2015, Page felt personally betrayed and severed ties.

This is a narrative Musk has recounted previously — including to author Walter Isaacson for his bestselling biography of Musk — but Tuesday marked the first instance he spoke of it under oath. Page has not responded, and it is important to note that everything Musk mentioned was in the context of a lawsuit. Nevertheless, as recently as 2023, he told tech podcaster Lex Fridman that he wished to reconcile: “We were friends for a very long time.”