Stefan Banach (1892-1945), the father of functional analysis, never knew who his mother was, a secret his father took to the grave. He survived the Nazi occupation of Lvov (now Lviv in Ukraine) feeding lice in a German Institute for infectious diseases together with many other Polish intellectuals, and did not live to enjoy the liberation for long.
He is a representative of an extraordinary flowering of mathematics in Poland between the two World Wars, together with Kuratowski, Mazurkiewicz, Nikodym, Orlicz, Sierpiński (of the gasket), Steinhaus (who famously said that Banach was his greatest discovery), Schauder, Ulam, Ważewski and Zaremba, give or take an accent. Banach is well known for his bizarre working habits: mainly in the Scottish Café (now a bank), where, inspired by beer, music and noise, he wrote on marble table tops till his wife gave him a sturdy notebook: the famous Scottish Book, which any customer could consult, and then try to solve a problem and win a prize (one such prize being a live goose). When the Scottish Café closed in the evenings, Banach used to go from one pub to another, drinking and thinking.
The premier Polish research establishment in mathematics is the Banach Centre in Warsaw, honouring the man who gave us Banach spaces, the Banach-Steinhaus theorem, and the perenially astonishing Banach-Tarski paradox, the heart’s desire of many a football team in extremis.
Actually I wanted to write about an omnivorous hedgehog. Well, next time.