I heard Jon’s lecture here at Western University back in April. I am not a mathematician, but from what I could understand, I was in the presence of genius. He ranged over so many topics and with such breezy fluency that I had the impression of immersing myself into the entirety of modern mathematics. Jon was affable, funny, versatile, curious and just an all-round pleasant person. His optimism seemed unconquerable. My family and I extend our deepest sympathy to all the grieving Borweins. [Vlad Tumanov, Associate Professor, Dept. of Modern Languages and Literatures, Western University, Ontario, Canada]