It's very productive scientifically; I often get some very good ideas for my research while hiking.

When I finished high school, it was clear to me that I would study mathematics, even if I also considered economics and psychology.

When I was born, my father owned a business called a 'reading circle'; folders containing an assortment of magazines were lent to customers for one week, then recollected and lent out again. The older the folder, the lower was the fee. This was a flourishing branch of industry.

I was born in Breslau on October 5th, 1930. At that time, Breslau, now called Wroclaw, belonged to Germany, and only German was spoken there. After the Second World War, Breslau became Polish, and the original German population was almost completely replaced by a Polish one. I have never visited Wroclaw after the war.